ACTION PATTERN OF PORCINE PANCREATIC ALPHA-AMYLASE ON 3 DIFFERENT SERIES OF BETA-MALTOOLIGOSACCHARIDE GLYCOSIDES

A technique for the investigation of the action pattern of porcine pan creatic amylase (PPA) has been developed by utilising as model substra tes 2-chloro-4-nitrophenyl (CNP) and 4-nitrophenyl (NP) beta-glycoside s of maltooligosaccharides of dp 4-8 and some NP derivatives modified at the nonreducing end with a 4,6-O-benzylidene (Bnl) group. The actio n pattern was investigated by the method of product analysis, using an HPLC method. The product pattern and cleavage frequency was very simi lar in the CNP- and NP-oligomers and showed that the glucopyranose res idue could be replaced by the aglycon group. Modification of the nonre ducing end of NP glycosides to give a 4,6-O-benzylidene-D-glucopyranos yl group indicated a favourable interaction between the Bnl group and the subsites (-3) and (-5) but an unfavourable one with subsite (-4), which resulted in a clear shift in the product pattern. The results ob tained with the digestion of the benzylidene-protected substrates conf irm a multiple attack mechanism for PPA. (C) 1997 Elsevier Science Ltd .