ACTION OF POLY(BETA-D-MANNURONATE)LYASE FROM TURBO-CORNUTUS ON OLIGOMERIC SUBSTRATES

A kinetic analysis of splitting oligomeric substrates by poly(beta-D-m annuronate)lyases (alginate lyases I, SP1 and SP2) from a marine mollu sk was done. Monomer and oligomers of mannuronate and guluronate were prepared by hydrolyzing poly beta-1,4-D-mannuronate and poly alpha-1,4 -L-guluronate from alginate with H2SO4, respectively, and thereafter b y gel filtration on a Bio-Gel P-2 column. Alginate lyases I apparently did not act on the trimer of mannuronate but did on the tetramer or t hose longer than that, indicating the increased k(cat)/K(m) with incre asing polymerization degree. The kinetic analyses suggest that the siz e of the subsite structure of the enzymes is most likely to be able to bind the linear pentamer of mannuronate units.