ABSTRACT
Proteins play central roles in all life processes, catalyzing biochemical reactions with remarkable specificity and serving as key structural elements in all cells and tissues. Progress in gene synthesis and genetic engineering have made it possible, in principle, to construct any desired amino acid sequence, and the era of “protein engineering” started in the early 1980s. Protein engineering should have tremendous theoretical and practical implications. It can be used both to explore fundamental questions about protein folding, structure, and function, and to design useful proteins for medical and industrial applications. Thermostability and specific activity of the new proteinase were about 10 and 40%, respectively, higher than those of thermolysin, the neutral proteinase from B. stearothermophilus. Thermostability of enzymes can be enhanced by single-amino acid substitutions. A single-amino acid substitution in kanamycin nucleotidyltransferase provided a new enzyme having higher thermostability than the natural one.
