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Molecular Biology: Folding Stuff
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Molecular Biology: Folding Stuff

Shape determines a protein's function. Determining that shape, though, is tricky. ABOUT 120,000 types of protein molecule have yielded up their structures to science That sounds a lot, but it isnt.

The techniques, such as X-ray crystallography and nuclear-magnetic resonance (NMR), which are used to elucidate such structures do not work on all proteins.
Some types are hard to produce or purify in the volumes required. Others do not seem to crystallize at all
a prerequisite for probing them with X-rays.

As a consequence, those structures that have been determined include representatives of less than a third of the 16,000 known protein families.
Researchers can build reasonable computer models for around another third, because the structures of these resemble ones already known. For the remainder, however, there is nothing to go on.


In addition to this lack of information about protein families, there is a lack of information about those from the species of most interest to researchers: Homo sapiens. Only a quarter of known protein structures are human. A majority of the rest come from bacteria.


This paucity is a problem, for in proteins form and function are intimately related.
A protein is a chain of smaller molecules, called amino acids, that is often hundreds or thousands of links long. By a process not well understood, this chain folds up, after it has been made, into a specific and complex three-dimensional shape. That shape determines what the protein does: acting as a channel, say, to admit a chemical into a cell; or as an enzyme to accelerate a chemical reaction; or as a receptor, to receive chemical signals and pass them on to a cell’s molecular machinery.
Almost all drugs work by binding to a particular protein in a particular place, thereby altering or disabling that protein
s function.

Designing new drugs is easier if binding sites can be identified in advance. But that means knowing the proteins structure. To be able to predict this from the order of the amino acids in the chain would thus be of enormous value. That is a hard task, but it is starting to be cracked.

 

 

Molecular: n. 分子

Crystallography: n. 晶体

nuclear-magnetic resonance (NMR): 核磁共振

Prerequisite: n. 先决条件

Homo sapiens: 智人

Enzyme: n.

the amino acids: 氨基酸

 

 

Edited by Bowman(Diao Tianyi), from 2015 Translation & Interpretation Class.

 
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