How much protein is present in the human body?

Answer 1

Information taken from wisegeek.com. It is estimated that the human body may contain over two million proteins, coded for by only 20,000 - 25,000 genes. We have http://wiki.answers.com/Q/l on just over a million proteins, taken mainly from http://wiki.answers.com/Q/l found in the ~100 genomes which have been fully sequenced as of 2007. The field that analyzes proteins in general and aims to exhaustively characterize all proteins in the human body is called proteomics. Proteins are long molecular chains made from the 20 basic building blocks of life, amino acids. The longest known protein, titin, also known as connectin, contains 26,926 amino acids. Titin is found in muscle and contributes to its passive stiffness. Because the 20 amino acids can be connected up in arbitrary sequences, the total space of possible proteins is exponential, with a value of approximately 2050,000, a tremendous number. The word protein comes from the Greek prota, meaning "of primary importance". This is a suitable name, as the central importance of proteins in the human body can not be overestimated. All biological organisms can be seen fundamentally as protein structures filled with water and sometimes supported by mineralized tissues called bone. For almost every protein there is another protein that can break it down. Proteins sometimes coalesce into mutually cooperative units called complexes, which perform useful biological functions. Every section of useful genetic information, found in the RNA or DNA, codes for a corresponding protein which goes on to fulfill a useful biological role.

Answer 2

Scientists have tried to answer that question, but it a difficult one to accurately answer, as proteins are complex and dynamic molecules. All else being equal a small change in the one of the underlying amino acids can render the protein inactive. So the question becomes, should all those inactive proteins be counted as well. And what about proteins that have exact similar properties but different amino acids combinations. For instance, let's take hemoglobin. It generally has 146 amino acids, but not all them are essential for the protein to be functional. So, if we a ask a question as to how many different amino acids are necessary for the protein to be known as the "hemoglobin" protein, then the answer depends on many things. Whenever changes in amino acid affects the physical structure of protein molecule, the affected protein becomes inactive. Then it no longer is the same protein. When the amino acids with similar chemical properties replace each other in a protein, then it will not affect the protein structure, and hence the protein remains the same albeit with a different amino acids composition. Also, some proteins are just a comfort for the cells and some proteins are very essential. Given that broad context under which proteins are classified, the total number of proteins in human body is estimated to be around 50,000.

Since every protein can be broken down by another protein, different type of proteins produced by a single cell organism ranges from two to four thousand. The common bacteria E-coli is predicted to have a total of 5,000 organic compound of which 3,000 are proteins. It is also estimated that human body has the ability to generate 2 million different types of proteins, coded by only 20,000-25,000 of our genes. The sum of proteins in biological organisms exceeds 10 million, but nobody has a clear picture of this. The field of research that focuses on proteins and catalogs all proteins in human body is known as Proteomics. The next step after completing the Human Genome project may be the Human Proteome project. The Human Proteome organization is being formed to achieve the goal of identifying and cataloging all the different proteins in the human body.