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 0.2 M 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 Mr of 24,868, separates across Spectrapore (13 kDa) membranes but not across Spectrapore with 3.5 kDa 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 13 kDa 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.
It is well known that Phaseolus species contains lectins of various specificities 1-4. Runner bean5 and different varieties of Ph.coccineus described by Ochoa et al6, are not specific to human blood groups. They react indistinctly with erythrocytes of the ABO system. However the lectin of Ph. lunatus (lima bean)7 is specific to the blood group type A, a classic example of that specificity. Sometime ago, we discovered a new lectin in a variety of edible bean of Ph. coccineus in the flora of the state of Oaxaca in Mexico, cultivated exclusively in the small community of Jamiltepec, near the Pacific coast, which presented strong hemagglutinating anti-A1 activity. In this report we describe a chromatographic technique for the isolation and purification of this lectin. The molecule is a tetramer with a molecular weight of 120 kDa. It requires Ca++ or Mg++ for activity, and it is inhibited by N-Acetylgalactosamine (GalNac) at concentration of 2.8 mM., NN' N' Triacetylchitotriose, 4-O(4-O-D-Galactopyranosyl) -D-Galatopyranosyl-D-Glucopyranose, and N' Diacetylchitobiose inhibited at moderate concentration (20mM). Conalbumin and ovoalbumin, also inhibited hemagglutination.
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 0.2 M 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 Mr of 24,868, separates across Spectrapore (13 kDa) membranes but not across Spectrapore with 3.5 kDa 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 13 kDa 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.
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