Protein folding

The characteristic protein aggregates seen in the brains of patients with Alzheimer's or Creutzfeldt-Jakob diseases are caused by the proteins adopting abnormal shapes called amyloid fibrils. In the 8 March Nature, Christopher Dobson and colleagues at the Oxford Centre for Molecular Sciences, UK, report that proteins outside the brain are also capable of assuming abnormal 'amyloid' structures.

In a physiological environment the muscle protein myoglobin is globular and its structure does not suggest a tendency to form amyloid fibrils. But in a screening process in which temperature, pH and buffers were varied, Fändrich et al found a chemical environment - 50 mM sodium borate, pH 9.0 at 65°C - that favoured conversion of myoglobin from its native structure into amyloid fibrils (Nature 2001, 410:165-166). They believe that organisms have evolved safeguards against this protein transition, but ageing or mutational changes could sometimes cause the protective mechanisms to break down.