Monday, March 14, 2016

Protein Levels

Proteins do much of the work of the cell, the basic biological unit. Proteins are made of subunits called amino acids, which in turn are made of atoms.

There are thousands of different kinds of proteins. I have posted previously about a set of proteins that work together, called ATP Synthase (ATPS, pronounced ATP sin-thase). The set acts together in this energy production machine. All organisms have ATPS (with the exception of viruses which are parasites and so benefit from ATPS indirectly).

Though I have pictures of ATPS elsewhere, I am putting this picture in my blog because it shows in one view the detail from three levels. The one on the upper left is the whole machine, a picture by David Goodsell at the link HERE. The next in line is the makeup of the amino acids in just one part of the machine (represented by their single letter symbols), which can be found at a protein database Uniprot HERE. As you can see, it is made up of 460 amino acids which have to be in correct order for the ATPS machine to work. (The database number here is for humans, but E. coli have the same number and the reference is P0ABB4). The next is a picture of the atomic arrangement of one amino acid (atoms are represented by their own separate letters).

If you are interested, you can see in a video at the link HERE how ATPS operates when protons flow through it because of an electrochemical gradient. The video lasts less than 4 minutes. The molecule that it makes is called ATP, or adenosine triphosphate (ah-den-oh-seen try-phosphate). This molecule is used to make proteins and DNA among other uses. Here is a picture of it:

Beyond the ATPS, other molecules are needed to set up the proton gradient that makes it work (seen at the same link HERE).

Some proteins can handle a few changes of amino acids, but some positions can't be changed or the protein will not work.

These proteins did not come about by chance, even in billions of years.