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 Protein Stucture and Function

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PostSubject: 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)


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Fer Salvatierra :)



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PostSubject: 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. Very Happy
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sofia steinsapir



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PostSubject: 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:

http://commons.wikimedia.org/wiki/File:Actin_with_ADP_highlighted.png
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pipomarmentini



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PostSubject: 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
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tomas_bala



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PostSubject: 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.
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carlos fiedler



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PostSubject: 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.

http://www.milkfacts.info/Structures/casein.JPG
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Nikola abello



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PostSubject: 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)
http://homepage.ntlworld.com/malcolmbowden/histones.jpg
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trini.muxica



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PostSubject: 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.

picture:

Question Suspect sorry sr. I couldn't put an image
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jorge barahona



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PostSubject: 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 .


http://en.wikipedia.org/wiki/File:Fibrinandligand.png






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BRYANS



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PostSubject: 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. Twisted Evil bounce Twisted Evil

photo: http://www.sigmaaldrich.com/etc/medialib/life-science/metabolomics/enzyme-explorer/elastin.Par.0001.Image.545.gif
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alexandra esnouf



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PostSubject: 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]
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alexandra esnouf



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PostSubject: Re: Protein Stucture and Function   Tue Oct 12, 2010 10:23 pm

http://course1.winona.edu/sberg/IMAGES/tubulin4.gif TUBULIN
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francisco.otero



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PostSubject: 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

Image:http://img.medscape.com/fullsize/migrated/496/917/nrc496917.fig3.gif[img][/img]
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Catalina Olavarria



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PostSubject: 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.
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fbowen



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PostSubject: 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.

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