The Grange Biology Forum
An open forum for members of the Grange Biology community to exchange ideas and information
Protein Stucture and Function
Posts : 52
Join date : 2010-06-29
|Subject: Protein Stucture and Function Wed Sep 22, 2010 12:20 pm|| |
Proteins are extemely important molecules in living organisms which have a wide range of important functions. Your forum task is too investigate the structure and function of one protein.
1) Re-read the textbook section on proteins for back ground information
2) Watch the video below for further examples of possible structures
3) Research on the internet and find one example of a protein which is important in living organisms. You must attach a picture and also write a summary of at least 150 words about the structure and function of the protein.
IMPORTANT: You must not choose any protein from the textbook. You must not choose any protein already selected by a classmate and included in the forum.
DUE DATE: You must post your forum by the start of your second class during Week 29 (11/10/10)
|Fer Salvatierra :)|
Posts : 3
Join date : 2010-08-03
|Subject: Re: Protein Stucture and Function Mon Sep 27, 2010 11:50 pm|| |
We all know the common protein, haemoglobin which transports iron throughout the body. But where does the body store and release this iron? Simple, with another protein called ferritin
, whose main function is to basically store and regulate the release of iron. Too much ferritin means too much iron, and low ferritin levels equals low iron levels. Ferritin is a globular structure in which iron is stored in various protective mechanisms (due to "free iron" which is toxic) to store iron in the tissue compartments. The structure influences the function; ferritin is made up of 24 protein subunits (which are folded into ellipsoids), this creates a hollow sphere in the middle of the structure where the iron is deposited. This contains two types of channels where the subunits meet: the 4-fold channel which is hydrophobic (non polar) because of the residue it contains (leucine), because it is non polar, it doesnt interact with iron and iron does not leave the channel, but electron transfer is done instead [ Fe(III) to Fe(II) ] ; the other type is called 3-fold channel, which is polar due to other residues (glutamate and aspartate), this polarity enables the passage of iron through the channel. So the structure and composition of ferritin is very important to the function because, if the 3-fold channel was non polar for instance, then the iron could not be released. Ferritin not combined with iron is called apoferritin. The different colors represent the two types of channels.
Posts : 4
Join date : 2010-06-30
|Subject: Re: Protein Stucture and Function Mon Oct 04, 2010 7:20 pm|| |
Actin is an unknown protein in contrast with others such as haemoglobin and keratin, it has a globular structure (globe-like) and it is the monomeric subunit of two types of filaments, these are microfilaments and thin filaments (which are part of the apparatus in muscle cells in charge of contracting). It is found in all eukaryotic cells, with the exception of the nematode sperm. Overall, Actin plays a fundamental and vital role in many cellular processes, almost always by means of interaction with other cellular membranes present in living organisms. These procedures are for example: muscle contraction, cell motility (or mobility), cell division, vesicle and organelle movement, cell signaling and last but not least the establishment of cell junctions and cell shape.
To conclude, we are able to observe that Actin is essential to us and other living organisms, as it takes part in many day to day processes inside our body that enables us live and survive correctly. In the link below you can see Actin’s globe-like structure:
|Subject: Protein Rhodopsin Mon Oct 04, 2010 10:25 pm|| |
Rhodopsin is the visual pigment of the vertebrate rod cells and responsible for both the formation of the photoreceptor cells and the first events in the perception of light. Rhodopsins are extremely sensitive to light, enabling vision in low-light conditions. Exposed to light, the pigment immediately photobleaches, and it takes about 30 minutes to regenerate fully in humans. Rhodopsin of the rods most strongly absorbs green-blue light and therefore appears reddish-purple, which is why it is also called "visual purple". It is responsible for monochromatic vision in the dark.
The crystal structure of rhodopsin provides significant insight concerning structure/activity relationships in visual pigment and related G-protein-coupled receptors. The specific arrangement of seven-transmembrane helices is stabilized by a series of intermolecular interactions.
Rhodopsin consists of the protein moiety opsin and a reversibly covalently bound cofactor, retinal. Opsin, a bundle of seven transmembrane helices connected to each other by protein loops, joins retinal (a photoreactive chromophore), which is located in a central pocket on the seventh helix at a lysine residue. Retinal lies horizontally with relation to the membrane. Each outer segment disc contains thousands of visual pigment molecules. About half the opsin is within the lipid bilayer. Retinal is produced in the retina from Vitamin A, from dietary beta-carotene. Isomerization of 11-cis-retinal into all-trans-retinal by light induces a conformational change (bleaching) in opsin continuing with metarhodopsin II, which activates the associated G protein transducin and triggers a second messenger cascade.
|Subject: Rhodopsin Photo Mon Oct 04, 2010 10:30 pm|| |
|Subject: My protein Thu Oct 07, 2010 8:50 pm|| |
The protein I choosed, is a protein that brings great benefits to athletes, it is hydrolyzed collagen. The protein collagen, is easily assimilated and although the content of those amino acids that promote muscle growth is poor, has an advantage that is appreciated by athletes because it contains significant amounts of proline and hydroxyproline, both used by our body as raw material for the production of collagen.
Collagen is a protein molecule to form fibers, the collagen fibers. These are found in all multicellular animals. They are secreted by cells of connective tissue such as fibroblasts and other cell types. It is the most abundant component of skin and bones, covering 25% of the total protein mass in mammals.
Function: The collagen fibers are structures that are made to resist tensile forces. Collagen has variable forms. Collagen´s diameter can different between tissues and it´s organization also. For example: in the skin of mammals are organized as wicker baskets, allowing the opposition to pull from multiple directions. In the tendons are the parallel beams that are aligned along the principal axis of traction. In the adult bone and cornea are arranged in thin, parallel to each other, while the fibers at right angles to the adjacent layers.
Posts : 1
Join date : 2010-08-11
|Subject: Julius marmentini KINESIN Protein Thu Oct 07, 2010 11:56 pm|| |
A kinesin is a protein belonging to a class of motor proteins found in eukaryotic cells. Kinesins move along microtubule cables powered by the hydrolysis of ATP (thus kinesins are ATPases). The active movement of kinesins supports several cellular functions including mitosis, meiosis and transport of cargo such as axonal transport. Most kinesins walk towards the plus end of a microtubule which, in most cells, entails transporting cargo from the centre of the cell towards the periphery. This form of transport is known as anterograde transport.
In recent years, it has been found that microtubule-based molecular motors (including a number of kinesins) have a role in mitosis (cell division). The mechanism by which the cytoskeleton of the daughter cell separates from that of the mother cell was unclear. It seems that motors organize the two separate microtubule asters into a metastable structure independent of any external positional cues
http://www.ks.uiuc.edu/Research/cell_motility/kinesin/movie1.gif link for kinesin structure
Posts : 3
Join date : 2010-08-03
|Subject: Insulin protein Tomas Baladron Mon Oct 11, 2010 1:39 pm|| |
foto : http://en.wikipedia.org/wiki/File:InsulinHexamer.jpg
The insulin protein is a hormone wich allows many types of cell take up glucose from the blood. Insulin prevents that fat is used as an energy source so when we dont have insulin cells do not take glucose from the blood and we use fat as a source of energy. Insulin also has another fuction wich affects memory, when insulin enters the human brain it benefits learning and memory but inside memory it benefits especially verbal memory. Its a peptide hormone wich has 51 amino acids it is produced in the pancreas as a hexamer ( six insulin molecules together). the hexamer acts as a monomer, why?, because its much more stable that the original insulin monomer (one insulin molecule) so the highly reactive insuline is protected, because although Insulin can be really good for the body and its fuctions, can cause diseases like insulinoma, diabetes mellitus and others.
Posts : 3
Join date : 2010-08-03
|Subject: Re: Protein Stucture and Function Mon Oct 11, 2010 8:45 pm|| |
casein, well-defined group of proteins found in milk, constituting about 80% of the proteins in cow's milk, but only 40% in human milk. Casein is a remarkably efficient nutrient, supplying not only essential amino acids, but also some carbohydrates and the inorganic elements calcium and phosphorus. The calcium caseinates form an insoluble white curd when acidified by hydrochloric acid or sulfuric acid, or when milk is soured by bacterial contaminants. Acid casein is used widely in cheese, adhesives, water paints, for coating paper, and in printing textiles and wallpaper. In neutral solutions the enzyme rennin converts one of the caseins to an insoluble curd; most of the protein in cheese is rennet casein curd. When treated with formaldehyde the curd forms casein plastic, used for manufacturing imitation tortoiseshell, jade, and lapis lazuli.
|Subject: Re: Protein Stucture and Function Mon Oct 11, 2010 11:01 pm|| |
Protein:Human serum albumin
Human serum albumin is the most abundant protein in human blood plasma. It is produced in the liver. Albumin comprises about half of the blood serum protein. It is soluble and monomeric.
• Maintains oncotic pressure
• Transports thyroid hormones
• Transports other hormones, particularly ones that are fat soluble
• Transports fatty acids to the liver
• Transports unconjugated bilirubin
• Transports many drugs; serum albumin levels can affect the half-life of drugs
• Competitively binds calcium ions (Ca2+)
• Buffers pH
• Serum albumin, as a negative acute-phase protein, is down-regulated in inflammatory states. As such, it is not a valid marker of nutritional status; rather, it is a marker in inflammatory states
• Prevents photodegradation of folic acid
Human serum albumin is a single peptide chain of 585 amino acids, held in three homologous domains by 17 disulfide bonds. Within each domain are two long loops plus one shorter loop. The S-S bonds provide stability while the intervening peptide strands allow for flexibility. The configuration includes 67% alpha helix and 10% beta turn.
Posts : 3
Join date : 2010-08-03
|Subject: Histones Tue Oct 12, 2010 5:52 pm|| |
Histones have many functions but they basically organize DNA into nucleosomes. They also help in gene regulation and they pack proteins in the cell nuclei. They act as spools where the DNA coils so it is compacted to fit the eukaryotes nuclei.
Histones are the main components of chromatin. There are 5 classes in which Histones can be classified (H1, H2A, H2B, H3 and H4). All but the Histones H1 have the same structure: two helix/turned and a long tail on one end of the amino acid. Both the tail and the core of the Histones can be modified.
Some of the 5 types of Histones have Helix dipoles form a “net” that accumulates a positive charge in negative phosphate in the DNA.
image ( Im sorry, could not put it into the text)
|Subject: Myosin Tue Oct 12, 2010 6:18 pm|| |
Myosin function is a mechanical work.
It is from a large family of motor proteins found in eukaryotic tissues while hydrolizing ATP.
It is one out of two major proteins constitutens responsable for muscle contraction.
It structure is arranged in long fillaments called thick fillaments that are parallel to the microfillaments of actin.
In mucle contraction the fillaments of actin and myosin, they chemically link and unlink between each other in a creeping or sliding action.
The energy for this reaction is supplied by adenosine triphosphate.
Myosin and actin also work in the motility of various non muscle cells.
It has two "heavy chains"
1) motor domintant, each heavy chain catalyzed ATP hydrolisis, and interacts with actin.
2)tail dominant in which heptad repeat sequence promote dimerization by forming an alpha-helical colied coil.
sorry i couldn't insert the images, but i send you their links
:image of myosin :example of the 2 heavy chains
Posts : 3
Join date : 2010-08-03
|Subject: Re: Protein Stucture and Function Tue Oct 12, 2010 6:22 pm|| |
Myosins are a large family of motor proteins found in eukaryotic tissues. They are responsible for actin-based motility. Following the discovery by pollard and korn of enzymes with myosin-like function in acanthamoeba castellanii, a large number of divergent myosin genes have been discovered throughout eukaryotes. Although myosin was originally thought to be restrincted from muscle cells, there is no single "myosin" but rather a huge superfamily of genes whose proteins products share the basic properties of acting binding, ATP hydrolysis and force transduction. Virtually all eukaryotic cells contain myosin isoforms. Some isoforms have specialized functions in certain cell types (such as muscle), while other isoforms are ubiquitous.
structure:Most myosin molecules are composed of a head, neck, and tail domain.
* The head domain binds the filamentous actin, and uses ATP hydrolysis to generate force and to "walk" along the filament towards the barbed (+) end (with the exception of myosin VI, which moves towards the pointed (-) end).
* the neck domain acts as a linker and as a lever arm for transducing force generated by the catalytic motor domain. The neck domain can also serve as a binding site for myosin light chains which are distinct proteins that form part of a macromolecular complex and generally have regulatory functions.
* The tail domain generally mediates interaction with cargo molecules and/or other myosin subunits. In some cases, the tail domain may play a role in regulating motor activity.
function:Multiple myosin II molecules generate force in skeletal muscle through a power stroke mechanism fuelled by the energy released from ATP hydrolysis. The power stroke occurs at the release of phosphate from the myosin molecule after the ATP hydrolysis while myosin is tightly bound to actin. The effect of this release is a conformational change in the molecule that pulls against the actin. The release of the ADP molecule and binding of a new ATP molecule will release myosin from actin. ATP hydrolysis within the myosin will cause it to bind to actin again to repeat the cycle. The combined effect of the myriad power strokes causes the muscle to contract.
sorry sr. I couldn't put an image
Posts : 1
Join date : 2010-08-18
|Subject: Re: Protein Stucture and Function Tue Oct 12, 2010 6:43 pm|| |
Fibrin is a fibrous protein involved in the clotting of blood, and is non-globular. It is a fibrillar protein that is polymerised to form a "mesh" that forms a hemostatic plug or clot over a wound site. Excessive generation of fibrin due to activation of the coagulation cascade leads to thrombosis (clot). premature Lysis of fibrin leads to haemorrhage.Disease of the liver can lead to a decrease in fibrinogen(soluble plasma glycoprotein, synthesised by the liver, that is converted by thrombin into fibrin during blood coagulation) production or the production of abnormal fibrinogen molecules with reduced activity (dysfibrinogenaemia). hemophiliacs: have reduced, absent, dysfunctional fibrin. The structure is mainly made up of single alpha helices .
Posts : 3
Join date : 2010-08-03
|Subject: Elastin Protein Tue Oct 12, 2010 10:03 pm|| |
Elastin is a protein that is elastic and allows tissues in the body to go back to their natural shape, after stretching or contracting. It used in places were mechanical energy is required to be stored. In humans elastin is encoded by the ELN gene. Is one of the two components of elastic fibres, the protein is rich in amino acids as glycine and proline, which form mobile hydrophobic regions bounded by crosslinks between lysine residues.
Elastin contributes with an important function in arteries as a medium for pressure wave propagation to help blood flow. It is abundant in the aorta. Elastin also plays a big role in the lungs, ligaments and skin.
Elastin is very important because with out it our muscles, some organs and ligaments could not come back to normal position and form after performing a movment.
Posts : 3
Join date : 2010-08-22
|Subject: Re: Protein Stucture and Function Tue Oct 12, 2010 10:21 pm|| |
Tubulin is a protein which constitutes microtubules, specifically alpha and beta tubulins together. This protein belongs to the globular type of proteins.
The particular structure of tubulin is defined as "heterodimer". This structure refers to those which are made up of a pair of polypeptides, these denominated monomers, which difference from each other by having different amino acid patterns. These monomers structure is made up of two beta sheets which are attached to a nucleotide binding site, a protein binding site, and a third substance. When these tubulin polymerize, they form long chains which finally form the microtubules. These microtubules allow the cells to go through mitosis, and this is only possible due to the flexibility the tubulin has, and therefore supplies the microtubule.[img][/img]
Posts : 3
Join date : 2010-08-22
|Subject: Re: Protein Stucture and Function Tue Oct 12, 2010 10:23 pm|| |
|Subject: Re: Protein Stucture and Function Tue Oct 12, 2010 11:16 pm|| |
Elastin is a very important protein as it allows tissues and organs to return to its original shape after being stretched and contracted. As its name says, it gives elasticity to our body. It is found in the walls of arteries, lungs, intestines and skin.
Elastin works with collagen in connective tissues. It functions as a perfect coil.
This protein has many internal linkages that make elastin resistant to the normal breakdown characteristic of most proteins. It also has a secondary structure.
Elastins are highly insoluble as they are mostly in a wet enviroment, so the hydrophilic sections are in favorable surroundings. The hydrophobic sections, on the other hand, "hide" from their watery surroundings by forming globular structures with less surface area than a straight chain. These globular hydrophobic sections have sometimes been called "oiled coils" by scientists.
|Subject: Re: Protein Stucture and Function Tue Oct 12, 2010 11:40 pm|| |
I chosed the Tau protein. This protein is found in neurons of the central nervous system. This is a very important protein, when they are not working properly they can cause Alzheimer's disease.
The Tau protein is essential for the stability and flexibility of microtubules which transport various nutrients and molecules within the cells. It works with Tubulin.
This protein is highly soluble.
The tau proteins are the products of alternative splicing from a single gene.
It has a primary structure
Posts : 3
Join date : 2010-08-03
|Subject: Re: Protein Stucture and Function Thu Oct 14, 2010 5:41 pm|| |
Bone Morphogenic Protein was discovered (published discovery) in 1961, as a result of constant study of the regenerative capacities of the bone, which brought attention to scientists around the world. They wanted to know why bones were hard, light and had amazing capabilities of healing over time if broken.
The protein BMP (bone morphogenic protein) makes, as its name says, bones and cartillegenous structures therefore making it a vital protein for all of us. Nowadays, it is known that not only does it make bones, but also helps in the majority of tissues in the body.
Xancers normally are a missregulation of the phagocytal capacities of BMP´s.
They work as follows, BMP's first interact with specific receptors on the cell surface, referred to as bone morphogenetic protein receptors (BMPRs), hereby, BMP's are present in most cells.
BMP's are used a lot in medicine, reinforcement of bones and even kidney treatments, due to the wide variety of them, they heve a large array of functions, here are the types with their specific function:
BMP Known functions Gene Locus
BMP1 *BMP1 does not belong to the TGF-β family of proteins. It is a metalloprotease that acts on procollagen I, II, and III. It is involved in cartilage development. Chromosome: 8; Location: 8p21
BMP2 Acts as a disulfide-linked homodimer and induces bone and cartilage formation. It is a candidate as a retinoid mediator. Plays a key role in osteoblast differentiation. Chromosome: 20; Location: 20p12
BMP3 Induces bone formation Chromosome: 14; Location: 14p22
BMP4 Regulates the formation of teeth, limbs and bone from mesoderm. It also plays a role in fracture repair. Chromosome: 14; Location: 14q22-q23
BMP5 Performs functions in cartilage development. Chromosome: 6; Location: 6p12.1
BMP6 Plays a role in joint integrity in adults. Chromosome: 6; Location: 6p12.1
BMP7 Plays a key role in osteoblast differentiation. It also induces the production of SMAD1. Also key in renal development and repair. Chromosome: 20; Location: 20q13
BMP8a Involved in bone and cartilage development. Chromosome: 1; Location: 1p35-p32
BMP8b Expressed in the hippocampus. Chromosome: 1; Location: 1p35-p32
BMP10 May play a role in the trabeculation of the embryonic heart. Chromosome: 2; Location: 2p14
BMP15 May play a role in oocyte and follicular development. Chromosome: X; Location: Xp11.2
|Subject: MYOSIN Thu Oct 14, 2010 7:35 pm|| |
Myosin is one of the two major protein constituents responsible for contraction of muscle. In muscle cells myosin is arranged in long filaments called thick filaments that lie parallel to the microfilaments of actin. In muscle contraction, filaments of actin alternately chemically link and unlink with those of myosin in a creeping or sliding action. The energy for this reaction is supplied by adenosine triphosphate. Myosin and actin also function in the motility of diverse non-muscle cells. In slime molds, for example, although present in much smaller quantities and forming shorter filaments, the interaction of the two proteins is employed to change cell shape and permit some movements.
cant attach the photo sorrry, there is the link
Posts : 2
Join date : 2010-08-09
|Subject: Protein Structure & Function Sat Oct 16, 2010 6:48 pm|| |
Proteins are essentials macromolecules that have many functions in our body's. Our body is made up of 45% of protein. Proteins are necessary for the reparing of tissue, nutrient transport, water controler, source of energy, mantains our hair and skin in good conditions. Essential for overall health.
Protein are organic macromolecules made up of linear amino acids chains.
Collagen is an example. Is found in all animal body's, including the human body. Is the most abudant protein our body's. Collagen is an essential structure component for all connective tissues. This includes: bone, cartilage, tendons, skin, and others. There are more than 19 types of collagen in our body. Some of the more importants are:
1. 50% of the protein that is inside the cartilage.
2. Helps support, strengthnes the wall of arteries, uterus, and intestine.
3. Main component if tendons, bone, and ligaments.
4. Fixes posible damages in basal lamina.
Collagen have a primary, secondary, and tertiary structure. Primary strucure formed of polypeptide. Secondary and tertiary structure consist on left twisted helix. They pass through endoplasmatic reticulum and golgi apparatus.
|Subject: itziar aldea, protein investigation Sun Oct 17, 2010 7:40 pm|| |
myosin (mī'usin) [key], one of the two major protein constituents responsible for contraction of muscle. In muscle cells myosin is arranged in long filaments called thick filaments that lie parallel to the microfilaments of actin. In muscle contraction, filaments of actin alternately chemically link and unlink with those of myosin in a creeping or sliding action. The energy for this reaction is supplied by adenosine triphosphate. Myosin and actin also function in the motility of diverse non-muscle cells. In slime molds, for example, although present in much smaller quantities and forming shorter filaments, the interaction of the two proteins is employed to change cell shape and permit some movements.
information taken from : myosin — Infoplease.com
Posts : 1
Join date : 2010-08-12
|Subject: Re: Protein Stucture and Function Tue Oct 19, 2010 6:06 pm|| |
casein is one of the most important proteins in the body, its abaut 20 per cent of the protein quantity in milk and other lactose pruducts such as cheese creame etc it is an important protein, It is relatively hydrophobic, making it poorly soluble in water. It is found in milk as a suspension of particles called casein micelles it is very difficult for it to denature. An intresting properrty of the casein molecule is its ability to form a gell or clot in the stomach. The ability to form this clot makes it very efficient in nutrient supply.
Casein has been documented to break down to produce the peptide casomorphin, witch some scientists believe difficults some health conditions, primarily autism.
|Subject: Re: Protein Stucture and Function Today at 12:45 am|| |