Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.108 (lactase)
 2,133 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The activities of various glycosidases in homogenates of the small-intestinal mucosa of one adult and two suckling echidnas, Tachyglossus aculeatus, were investigated. The activities of lactase (beta-D-galactosidase), beta-N-acetylglucosaminidase, neuraminidase and alpha-L-fucosidase were higher in the sucklings than in the adult animal. Maltase and isomaltase activities were lower. Sucrase and cellobiase activities were absent or present in trace amounts only. The lactase activity had a pH optimum of 4.0-4.5, was predominantly in the soluble fraction following ultracentrifugation and was inhibited by p-chloromercuribenzene sulfonate, suggesting that it was due to a lysosomal acid beta-galactosidase and not a brush-border neutral lactase. The maltase activity of the sucklings also had the characteristics predominantly of a lysosomal acid hydrolase. It is proposed that in suckling echidnas, the oligosaccharides (mainly neuraminyllactose and fucosyllactose) of the mother's milk are digested intracellularly by lysosomal enzymes, rather than at the brush border, of the epithelial cells of the small-intestinal mucosa.
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PMID:Intestinal glycosidase activities in one adult and two suckling echidnas: absence of a neutral lactase (beta-D-galactosidase). 641 47

The complex between lactase (beta-D-galactoside galactohydrolase, EC 3.2.1.23) and phlorizin hydrolase (glycosyl-N-acylsphingosine glycohydrolase, EC 3.2.1.62) has been purified from the proximal and distal regions of the small intestine of suckling rats. The two enzymes behaved differently on DEAE-cellulose ion-exchange chromatography and during electrophoresis in the presence and absence of sodium dodecyl sulphate (SDS), but they have very similar cyanoge bromide cleavage patterns. Kinetic studies on the proximal and distal enzymes showed the same pH optimum of 6.0 and the same heat stability at 45 degrees C, but a small difference in Km. Treatment of both enzymes with fucosidase, mannosidase or N-acetylhexosaminidase did not affect enzymic activity or electrophoretic mobility. Neuraminidase digestion abolished the electrophoretic differences and gave two active enzymes with similar isoelectric points.
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PMID:Isolation and characterization of the proximal and distal forms of lactase-phlorizin hydrolase from the small intestine of the suckling rat. 677 1

The activities of various glycosidases in homogenates of the small intestinal mucosa of two adult and 18 suckling tammar wallabies (M. eugenii) aged from 6 to 50 weeks were investigated. Lactase (beta-D-galactosidase), beta-N-acetylglucosaminidase, alpha-L-fucosidase and neuraminidase activities were high during the first 34 weeks post partum and then declined to very low levels. Maltase, isomaltase, sucrase and trehalase activities were very low or absent during the first 34 weeks, and then increased. The lactase activity was unusual in being greater in the distal than the middle or proximal thirds of the intestine, and in its low pH optimum (pH 4.6), inhibition by p-chloromercuribenzene sulfonate but not by Tris, and lack of cellobiase activity. These properties are those of a lysosomal acid beta-galactosidase rather than of a brush border neutral lactase. The maltase activity had the characteristics of a lysosomal acid alpha-glucosidase early in lactation and of a brush border neutral maltase in adult animals. The significance of these findings is discussed in relation to changes in dietary carbohydrates during weaning and to the mode of digestion of milk carbohydrates by the pouch young.
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PMID:Intestinal lactase (beta-galactosidase) and other glycosidase activities in suckling and adult tammar wallabies (Macropus eugenii). 678 21