Purification and characterization of polygalacturonase from banana fruit.
Polygalacturonase isoenzyme 3 (PG-3) was purified to homogeneity with a specific activity of 0.7 mu katal mg-1 protein from banana fruit pulp. The purified enzyme was a glycoprotein with ca. 8% carbohydrate. The molecular weight of the native enzyme was found to be 90 +/- 10 kDa with a subunit molecular weight of 29 +/- 2 kDa. The enzyme exhibited optimum activity at pH 4.3 and temperature 40 degrees C with activation energy 35.4 kJ mol-1. A unique property of the enzyme was the requirement of -SH groups for the enzyme activity. The enzyme was inhibited by p-CMB and activated by 2-ME and DTT. The inhibition of p-CMB could be reversed by DTT. The enzyme contained eight free -SH groups. The Km of the enzyme was 0.15% for polygalacturonic acid.
Pathak
N
N
Department of Biochemistry, University of Lucknow, India.
Mishra
S
S
Sanwal
G G
GG
D002241:Carbohydrates / Q000032:analysis; D004591:Electrophoresis, Polyacrylamide Gel; D008970:Molecular Weight; D011096:Polygalacturonase / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D013438:Sulfhydryl Compounds / Q000378:metabolism; D013696:Temperature; D019862:Zingiberales / Q000201:enzymology*
D002241:Carbohydrates; D013438:Sulfhydryl Compounds; D011096:Polygalacturonase