Chitinase Activity from Candida albicans and its Inhibition by Allosamidin

Abstract

Candida albicans chitinase isolated using the Dyno-Mill disruption technique was characterized using an improved radiometric assay procedure. The enzyme had apparent temperature and pH optima of 45 "C and 6.5, respectively. The preparation yielded an apparent K , of 3.9 mg chitin ml-1 [ 17.6 mM-N-acetylglucosamine (GlcNAc) equivalents] and V of 2.3 nmol GlcNAc formed min-l (mg protein)-'. The potential of the streptomycete antibiotic allosamidin as an antifungal agent is discussed in view of its dose-dependent inhibition of C. albicans chitinase activity (ICs0 = 0.3 VM). Allosamidin was a potent competitive inhibitor of enzyme activity (Ki = 0-23 VM).

Chemical modification studies of the active centre of Candida albicans chitinase and its inhibition by allosamidin

“…It has poorer activity against bacterial chitinases Somers et al, 1987;Koga et al, 1987) and no detectable activity against the plant chitinase from yam (Koga et al, 1987). This antibiotic was also shown to be a competitive inhibitor of C. albicans chitinase, in studies with the use of tritiated chitin as a substrate (Dickinson et al, 1989). In this work we confirmed the inhibitory potency of allosamidin, using the soluble substrate MeUmb(GlcNAc),.…”

“…A specific inhibitor of some chitinases has recently been characterized, as a novel antibiotic from Streptomyces species, and has been named allosamidin or A82516 (Somers et af., 1987). The chitinase from C. albicans is susceptible to allosamidin (Dickinson et al, 1989). We present here results of a study of the mode of action of the chitinase of C. albicans, as elucidated by the effects of selected group specific reagents and of allosamidin on a semi-purified preparation.…”

“…In the yeast Saccharomyces cerevisiae, it is involved in separation of cells after budding (Kuranda & Robbins, 1991 ;Cabib et al, 1992) and in filamentous fungi it is probably involved in hyphal growth and branching and in spore germination (Gooday et al, 1986; Rast et al, 1991). Chitinase activity has been described from yeast cells of the dimorphic human pathogenic fungus Candida albicans (Barrett-Bee & Hamilton, 1984; Dickinson et al, 1989). Because of its roles in fungal growth, chitinase presents a target for potential anti-fungal agents.…”

Structure-Based Exploration of Cyclic Dipeptide Chitinase Inhibitors

“…1,2 The fungal human pathogen Candida albicans utilizes chitinases during cell division to separate daughter cells. 3 Insect ecdysis also relies on chitinases. 4 The eggs of the nematode gastrointestinal parasite of mice, Heligmosomoides polygyrus, express increasing levels of chitinase with age up to hatching, 5 and Entamoeba invadens, a model for pathogenic amoebic encystation, produces chitinase during encystation.…”

Intracellular chitinase gene from Rhizopus oligosporus: molecular cloning and characterization

“…These results suggest that chitinase I11 could be most active in the cells in contact with membrane-or cell-wall structures. In M. rouxii and Candida albicans cell extracts the presence of membrane-bound chitinases is suggested and the activities of these enzymes are inhibited by treatment with phospholipases and stimulated by detergents (Humphreys & Gooday, 1984;Dickinson et al, 1991). A 45 kDa chitinase was purified from the cytosolic fraction of C. albicans.…”