Sunday, November 24, 2013

Fred Sanger, Protein Sequences and Evolution Versus Science

Are Proteins Random?

The passing of the great biochemist Frederick Sanger this week reminds us of another one of evolution’s many scientific failures, namely the view that protein sequences are random. Here is how one obituary explains it:

… Chibnall and Sanger believed that there might be a real possibility of determining the exact chemical structure of proteins. This idea was controversial at the time as, although the 20 or so amino acids that can go to make up proteins were known, most scientists believed the arrangement of different amino acids in a protein to be random. One professor had even produced a complex mathematical formula that would express this random function. Thus, when Chibnall tried to get Sanger a grant from the Medical Research Council to work on protein structure, the grant was refused because “everyone knew” that the pattern of amino acids in a protein was random.

Nevertheless, Sanger scraped together enough money from various sources to start work. From 1944 to 1951 he held a Beit Memorial Fellowship for Medical Research; and in 1951, by which time the Medical Research Council had come to recognise the importance of his work, he became a member of the MRC’s external staff.

The protein which Sanger chose for his research was insulin which, as well as being relatively small in size and available in large quantities, had strong clinical implications in the understanding of diseases such as diabetes. He developed a method of marking the end amino acid and splitting it off from the insulin. The end amino acid was then identified and the process repeated. By this painstaking method, Sanger showed that a molecule of insulin contains two peptide chains made of two or more amino acids that are linked together by two disulphide bonds. It took eight more years finally to identify the 51 amino acids that make up insulin.

The evolutionary mythology of randomness at the molecular level persisted for many years to come. Here is how the famous French evolutionist, Jacques Monod, described Sangar’s breakthrough work in the evolutionary classic Chance & Necessity:

The first description of a globular protein’s complete sequence was given by Sangar in 1952. It was both a revelation and a disappointment. This sequence, which one knew to define the structure, hence the elective properties of a functional protein (insulin), proved to be without any regularity, any special feature, any restrictive characteristic. Even so the hope remained that, with the gradual accumulation of other such findings, a few general laws of assembly as well as certain functional correlations would finally come to light. Today our information extends to hundreds of sequences corresponding to various proteins extracted from all sorts of organisms. From the work on these sequences, and after systematically comparing them with the help of modern means of analysis and computing, we are now in a position to deduce the general law: it is that of chance. To be more specific: these structures are “random” in the precise sense that, were we to know the exact order of 199 residues [i.e., amino acids] in a protein containing 200, it would be impossible to formulate any rule, theoretical or empirical, enabling us to predict the nature of the one residue not yet identified in the analysis.

To say that in a polypeptide the amino acid sequence is “random” may perhaps sound like a roundabout admission of ignorance. Quite to the contrary, the statement expresses the nature of the facts. [Vintage Books Edition, 1972, 96]

In fact the protein amino acid sequences are not random any more than an English sentence is random. But if you don’t know the language, it may appear random, such as this sequence of letters: “modnartonsierutan”. But appearances can be deceiving. Reverse the order and add a few spaces, and the sequence becomes: “nature is not random”.

Standard tests of randomness show that English text, and protein sequences, are not random. Nonetheless evolutionists continued to promote this view. A 1986 paper described globular proteins as having “random sequences” and that the physical requirements for such proteins are commonly inherent in random sequences.

Likewise as late as 1990 evolutionists claimed that the distribution of oily amino acids in protein sequences could not “be distinguished from that expected for a random distribution.” Thus proteins could have “originated from random sequences.”

All of this proved to be false and is yet another false prediction of the metaphysically-driven evolutionary thought.

1 comment:

  1. prof premraj pushpakaran -- 2018 marks the 100th birth year of Frederick Sanger!!!