Subunit Structure of Karatasin, the Proteinase Isolated from Bromelia plumieri(karatas)(Biological Chemistry)

概要

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Close to 15 % of the karatasin proteinase activity in the fruit juice of Bromelia plumieri(karatas) is present outside dialysis Visking tubing in 7 days in 0.2M acetate buffer (pH) 3.5 or 6.5) containing phenyl mercuric acetate. The small proteinase(s), distinct from the 85 % activity in juice due to nondialysable karatasin with a reported M_r of 24,868, separates across Spectrapore (13kDa) membranes but not across Spectrapore with 3.5kDa average pore diameter. The dialyzed proteinase is named karatasin-D (K-D). Purified non-Dialysable karatasin can be dissociated to what seems to be K-D by incubation in a buffer solution, containing SDS and 2-mercaptoethanol with phenyl mercuric acetate, in dialysis experiments for 8 days at room temperature using Spectrapore 13kDa tubing. Thus, native karatasin in B. plumieri fruit juice seem to be the result of association of 2 small molecular mass K-D subunits, linked together by disulfide bonds and electrostatic forces, in equilibrium with small amounts of free K-D molecules. The amino acid composition and partial sequence of karatasin up to the 14th position from the amino terminus have discrete analogies with papain and with stem bromelain.
社団法人日本農芸化学会の論文
1990-01-23