Isolation and properties of α-D-mannosidase from human kidney

Abstract

Alpha-D-Mannosidase activity exists in three forms that can be separated by DEAE-cellulose chromatography, alpha-D-Mannosidase was isolated from human kidney in a homogeneous state, and was purified 2100-fold, with p-nitrophenyl alpha-D-mannoside as substrate. The purified alpha-D-mannosidase was practically free from all other glycosidases tested. The Km of the synthetic substrate with the enzyme was 1 X 10(-3) M and the pH optimum 4.5. It was inhibited by heavy metals, sodium dodecyl sulphate, urea and compounds that react with the thiol groups, and was activated by Zn2+, Na+, 2-mercaptoethanol, human albumin and gamma-globulin. The mol. wt. of the enzyme was estimated to be 180 000 +/- 4500. After pretreatment with 2-mercaptoethanol and sodium dodecyl sulphate, alpha-D-mannosidase dissociated into subunits of mol. wts. of 58 000 +/- 600 and 30 000 +/- 380 respectively. Subunits of the same molecular weights were also obtained after the enzyme was heated at 100 degrees C.

Purification and Chemical Characterization of Human Acidic Alpha-D-Mannosidase

“…The multiple isozymes are often related to the involvement of two or more genetically determined nonidentical subunits for consti tution of an enzyme. Several authors have suggested that acidic a-mannosidase is a dimer [12,17]. However, no clear single sub unit band was evident on their SDS electro phoresis gels.…”

Multiscale Mechanical Simulations of Cell Compacted Collagen Gels

“…The collagen gel microstructure was approximated by a collection of 3D fiber networks that have been shown to resemble the structure and heterogeneity observed experimentally [1,2]. In this study, each element in the FE mesh was randomly assigned a 3D fiber network containing on average 323 ± 26 cross-linked fibers.…”

“…Recently, it has been demonstrated that in addition to soluble biochemical factors, the properties of the surrounding extracellular matrix (ECM) and the local mechanical environment profoundly influence cell behavior [1][2][3][4][5]. The mechanical environment is controlled in part by the composition and stiffness of the local ECM and by the manner in which physical forces applied at the tissue-level propagate down to the cellular level.…”

Glycolipid and Glycoprotein Degradation

“…The activity can be restored immediately by the addition of excess zinc. Thus, the loss of Zn2' during purification may in some cases account for the poor recoveries [e.g., see (521)l and differences in purity and in incubation conditions may explain controversial results on ZnZ + requirement of the enzyme (519,(522)(523)(524)526,527,541). In the presence of 1-mM Zn" , a-mannosidase is stable at 65"C, pH 6.0 for at least 1 h (537).…”