Peptide and protein hydrolysis by microwave irradiation.

The recent advances in instrumentation for amino acid analysis and highperformance liquid chromatography (HPLC) have shortened the net analysis time for amino acid analysis to less than an hour for each individual sample. Therefore the rate-determining and most essential step of a successful amino acid analysis now lies in the skillful preparation of protein hydrolysates. The commonly used conventional protocol of Hirs et al. [l] utilizes 6 M hydrochloric acid and llO-120°C for more than 24 h and has been the method of choice for the past thirty years. Although the recent development of HPLC amino acid analysis [ 2,3] coupled with gas phase hydrolysis of protein samples [4] has been widely used, the reproducible and complete amino acid analysis data for most proteins are not easily obtained, except in some cases of short peptides. We have introduced a rapid method of microwave heating for the facile preparation of protein and peptide hydrolysates [5,6]. This paper reports refinements of the method, and establishes microwave irradiation as a rapid and novel means of protein hydrolysis with special regard to its general application to amino acid analysis. It provides a radical method of protein and peptide hydrolysis via commercial microwave ovens and specially designed TeflonPyrex tubes with the potential of on-line automation of protein hydrolysis and analysis.