Purification and properties of glycoprotein processing. cap alpha. -mannosidase from mung bean seedlings

Journal Article · Sun Jun 01 04:00:00 EDT 1986 · Plant Physiol.; (United States)

OSTI ID:6992606

Szumilo, T; Kaushal, G P; Hori, H; Elbein, A D

The microsomal fraction of mung bean seedlings contains mannosidase activities capable of hydrolyzing (/sup 3/H) mannose from the (/sup 3/H)Man/sub 9/GlcNAc as well as for releasing mannose from p-nitrophenyl-..cap alpha..-D-mannopyranoside. The glycoprotein processing mannosidase was purified by conventional methods and also by affinity chromatography on mannan-Sepharose and mannosamine-Sepharose. The final enzyme preparation contained a trace of aryl-mannosidase, but this activity was inhibited by swainsonine whereas the processing enzyme was not. The pH optimum for the processing enzyme was 5.5 to 6.0, and activity was optimum in the presence of 0.1% Triton X-100. The enzyme was inhibited by ethylenediaminetetraacetate while Ca/sup 2 +/ was the most effective cation for reversing this inhibition. Mn/sup 2 +/ was considerably less effective than Ca/sup 2 +/ and Mg/sup 2 +/ was without effect. The processing mannosidase was inhibited by ..cap alpha..1,2- and ..cap alpha..1,3-linked mannose oligosaccharides whereas free mannose and ..cap alpha..1,6-linked mannose oligosaccharides were ineffective. Mannosamine was also an inhibitor of this enzyme. The aryl-mannosidase and the processing mannosidase could also be distinguished by their susceptibility to various processing inhibitors. The processing mannosidase was incubated for long periods with (/sup 3/H)Man/sub 9/GlcNAc and the products were identified by gel filtration. Even after a 24 hour incubation, the only two radioactive products were Man/sub 5/GlcNAc and free mannose. Thus, this enzyme appears to be similar to the animal processing enzyme, mannosidase I, and is apparently a specific ..cap alpha..1,2-mannosidase.

• Research Organization: Univ. of Texas Health Science Center, San Antonio
• OSTI ID: 6992606
• Journal Information: Plant Physiol.; (United States), Journal Name: Plant Physiol.; (United States) Vol. 81:2; ISSN PLPHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
BACTERIA
CHEMICAL PROPERTIES
ENZYME ACTIVITY
ENZYME INHIBITORS
ENZYMES
FOOD
GLYCOSYL HYDROLASES
HYDROLASES
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LEGUMINOSAE
MICROORGANISMS
MUNGBEANS
PLANTS
PURIFICATION
RHIZOBIUM
SEEDLINGS
SEEDS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VEGETABLES