Kinetics and thermodynamics of a novel endoglucanase (CMCase) from Gymnoascella citrina produced under solid-state condition.
Gymnoascella citrina produced two isoforms of endoglucanases (CMCase-I and -capital I, Ukrainiancapital I, Ukrainian) under solid-state condition. Purified CMCase-I was novel because it was apparently holoenzyme in nature. The enzyme was monomeric as its native and subunit mass were almost the same, i.e., 43 and 42 kDa, respectively. Ea for carboxymethylcellulose (CMC) hydrolysis was 36.2 kJ mol(-1). The enzyme was stable over a pH range of 3.5-6.5, while temperature optimum was 55 degrees C. Vmax, Km and k (cat )for CMC hydrolysis were 39 U mg(-1) protein, 6.25 mg CMC mL(-1) and 27.5 s(-1), respectively. The pKa1 and pKa2 of ionizable groups of active site were 2.8 and 7.4, respectively. Thermodynamic parameters for CMC hydrolysis were as follows: DeltaH*=33.5 kJ mol(-1), DeltaG*=70.42 kJ mol(-1) and DeltaS*=-114.37 J mol(-1) K(-1). The removal of metals resulted into complete loss of enzymatic activity and was completely recovered in the presence of 1 mM Mn2+, whereas inhibition initiated at 5 mM. The other metals like Ca2+, Zn2+ and K1+ showed no inhibition up to 7 mM, Co2+ completely inhibited the activity, while Mg2+ could not recover the initial activity up to 7 mM. So we are reporting for the first time, kinetics and thermodynamics of CMCase-Iota from G. citrina.
Jabbar
Abdul
A
Department of Chemistry, G.C. University, Faisalabad, Pakistan.
Rashid
Muhammad Hamid
MH
Javed
Muhammad Rizwan
MR
Perveen
Raheela
R
Malana
Muhammad Aslam
MA
D000645:Ammonium Sulfate / Q000378:metabolism; D001203:Ascomycota / Q000201:enzymology*; D002480:Cellulase / Q000096:biosynthesis* / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism*; D002853:Chromatography, Liquid; D003470:Culture Media; D005285:Fermentation; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D008670:Metals / Q000494:pharmacology; D008970:Molecular Weight; D013696:Temperature; D013816:Thermodynamics
D003470:Culture Media; D008670:Metals; D002480:Cellulase; D000645:Ammonium Sulfate