PURIFICATION AND PARTIAL CHARACTERIZATION OF A LECTIN FROM THE SEEDS OF DIOCLEA GUIANENSIS1

A lectin was purified from seeds of Dioclea guianensis by Sephadex G-50 affinity chromatography. Apparent homogeneity of the lectin was demonstrated by native polyacrylamide gel electrophoresis, chromatography on DEAE- and CM-Sepharose, and immunochemistry. The lectin showed a carbohydrate specificity for D-mannose (D-glucose)-binding, had a requirement for Ca^?2 and Mn^?2, contained no covalently bound carbohydrate and had an amino acid composition characterized by high content of aspartic acid, serine and threonine, and low levels of sulfur-containing amino acids. At pH 7.5 it exists as two species of molecular weight about 100 and 47 kD and in dissociating solvents three subunits of approximate size of 30, 18 and 12 kD were obtained. The lectin agglutinated erythocytes from rabbit and chicken but not from human, cow, sheep, goat or pig and was toxic to brine shrimp (Artemia salina) larvae. It was relatively heat-stable, retaining half of its original activity even after 90 min at 70°C.     

Influence of transmembrane pressure on the separation of caprine milk oligosaccharides from protein by cross‐flow ultrafiltration

Goat milk shows similarities with human milk in terms of their oligosaccharides composition. However, the supplementation of goat milk protein in infant formulae is not allowed, which demands a previous separation of oligosaccharides from protein. The purpose of this study was to evaluate the effect of transmembrane pressure on the fractionation of oligosaccharides, protein, lactose and calcium in the diafiltration of caprine milk through a 50 kDa tubular ceramic membrane. Permeates with more than 99% of the original oligosaccharides were obtained after four diavolumes. It was seen that transmembrane pressure had a great influence on filtration time and protein transmission.