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P K Masson

Publications and source records attributed to P K Masson.

9 recordsLinked to original sources
PubMed1976

Neutral alpha-mannosidase activity in human serum.

Two types of alpha-mannosidase (alpha-D-mannoside mannohydrolase, EC 3.2.1.24) with neutral pH optima exist in serum. The activity with an optimum between pH 6.0 and 6.4 is similar to alpha-mannosidase C, described earlier in tissues. The second activity, with a pH optimum between pH 5.2 and 5.8 is the dominant form in serum. These two forms can be differentiated from each other by gel-filtration, chromatography on DEAE-cellulose or chromatography on Concanavalin-A Sepharose. Using the chromatographic techniques, the serum type neutral activity co-elutes with the acidic forms of the enzyme. However, these two forms can be easily distinguished by effect of pH, heating or inhibition by the substrate methyl-alpha-D-mannopyranoside. The presence of the serum type alpha-mannosidase activity is discussed with respect to mannosidosis, a lysosomal storage disease.

Disaccharidases↗
PubMed1976

Structural determination of three glycoasparagines isolated from the urine of a patient with aspartylglycosaminuria.

Three different glycoasparagines have been isolated from the urine of a patient with aspartylglycosaminuria and their structures determined using sugar, amino acid and methylation analysis, enzymic degradation and measurements of the optical rotations. The structures were 2-acetamido-1-N-(4'-L-aspartyl)-2-deoxy-beta-D-glucopyranosylamine (yield 135 mg/l) beta-D-galactopyranosyl-(1 leads to 4)-2-acetamido-1-N-(4'-L-aspartyl)-2-deoxy-beta-D-glucopyranosylamine (yield 35 mg/l), and alpha-D-mannopyranosyl-(1 leads to 6)-beta-D-mannopyranosyl-(1 leads to 4)-2-acetamido-2-deoxy-beta-D-glucopyranosyl-(1 leads to 4)-2-acetamido-1-N-(4'-L-aspartyl)-2-deoxy-beta-D-glucopyranosylamine (yield 30 mg/l). The first two compounds have previously been described, whereas the third compound is different from any of the glycoasparagines isolated before.

Acetylglucosamine↗
PubMed1975

Specificity studies on alpha-mannosidases using oligosaccharides from mannosidosis urine as substrates.

Oligosaccharides containing terminal non-reducing alpha(1 leads to 2)-, alpha(1 leads to 3)-, and alpha(1 leads to 6)-linked mannose residues, isolated from human and bovine mannosidosis urines were used as substrates to test the specificities of acidic alpha-mannosidases isolated from human and bovine liver. The enzymes released all the alpha-linked mannose residues from each oligosaccharide and were most effective on the smallest substrate. Enzyme A in each case was less active on the oligosaccharides than alpha-mannosidase B2, even though the apparent Km value for the substrates was the same with each enzyme. The human acidic alpha-mannosidases were also found to be more active on substrates isolated from human rather than bovine mannosidosis urine. Human alpha-mannosidase C, which has a neutral pH optimum when assayed with a synthetic substrate, did not hydrolyse any of the oligosaccharides at neutral pH, but was found to be active at an acidic pH.

Animals↗
PubMed1975

The relationship between different forms of human alpha-mannosidase.

The tissue distribution and some properties of human alpha-mannosidase (alpha-D-mannoside mannohydrolase EC 3.2.1.24) have been studied. The acidic forms of the enzyme were fairly stable, whereas the neutral forms easily lost enzymic activity. The acidic forms were sensitive to neuraminidase but the neutral forms were unaffected. The experiments indicate that the acidic components are closely related to each other, differing only in sialic acid content and possibly conformation. The neutral forms of the enzyme are probably quite different from the acidic forms both in structure and cellular function.

Brain↗