'One of the men who shared the Nobel Prize in 1961 for the
pioneering x-ray crystal structure analyses of myoglobin and hemoglobin,
M. F. Perutz of Cambridge, has characterized this as the Matthew
Effect: "For to every one who hath, will more be given,
and he will have abundance; but from him who hath not, even that
which he hath will be taken away." (Matthew 25:29)
These two globular protein molecules are nearly all a-helical.
In other such proteins, the chain is folded in a less regular manner,
and several nearly parallel extended chains can be cross-linked
by hydrogen bonds to form a sheet resembling a small region of silk.
Such a silklike sheet often acts as the central core of a globular
protein, with a helices packed against
it on either side to form a compact molecule. We will discuss protein
structures again in Chapter 24 and see three enzymes that have very
little a-helical structure.
Right: Max Perutz, who shared the 1962 Nobel prize in chemistry
with John Kendrew. (Photograph from the MRC, Laboratory of Molecular
Biology, Cambridge, UK.)