title: Purification and the effect of manganese ions on the activity of carboxymethylcellulases from Aspergillus niger and Cellulomonas biazotea.
abstract: Carboxymethylcellulases (CMCases) from Aspergillus niger and Cellulomonas biazotea were purified by a combination of ammonium sulfate precipitation, anion-exchange and gel-filtration chromatography with a 12- and 9-fold increase in the purification factor. The native and subunit molar mass of CMCase from A. niger were 40 and 25-57 kDa, respectively, while those from C. biazotea were 23 and 20-30 kDa, respectively. Low concentrations of Mn2+ activated the enzymes from both organisms (mixed activation) with apparent activation constants of 0.80 and 0.45 mmol/L of CMCases from A. niger and C. biazotea, respectively, while at higher CMC concentrations Mn2+ inhibited the enzymes (mixed and partial uncompetitive inhibition). The reason for this complex behavior is that more than one Mn2+ bind to the same enzyme form with the apparent average inhibition constants of 2.7 and 1.3 mmol/L for CMCases from A. niger and C. biazotea, respectively.
authors.affiliation: National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Pakistan.
authors.forename: K S
authors.initials: KS
authors.lastname: Siddiqui
authors.forename: M J
authors.initials: MJ
authors.lastname: Azhar
authors.forename: M H
authors.initials: MH
authors.lastname: Rashid
authors.forename: T M
authors.initials: TM
authors.lastname: Ghuri
authors.forename: M I
authors.initials: MI
authors.lastname: Rajoka
mesh_terms: D000192:Actinomycetales / Q000201:enzymology*; D001234:Aspergillus niger / Q000201:enzymology*; D001426:Bacterial Proteins / Q000737:chemistry / Q000187:drug effects* / Q000302:isolation & purification / Q000378:metabolism; D001665:Binding Sites; D002480:Cellulase; D005656:Fungal Proteins / Q000737:chemistry / Q000187:drug effects* / Q000302:isolation & purification / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000187:drug effects* / Q000302:isolation & purification / Q000378:metabolism; D007700:Kinetics; D008345:Manganese / Q000494:pharmacology*; D008970:Molecular Weight; D011487:Protein Conformation / Q000187:drug effects; D013329:Structure-Activity Relationship
chemical_list: D001426:Bacterial Proteins; D005656:Fungal Proteins; D008345:Manganese; D006026:Glycoside Hydrolases; D002480:Cellulase; C019826:carboxymethylcellulase