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Glyoxalase I and glyoxalase II from the outer green rind of Aloe vera leaves were purified by (matrix) affinity ligand-enzyme binding methods. The purified enzymes exhibited single protein bands on SDS-PAGE electrophoresis, with MW values of approximately 44,000 and 27,000 for glyoxalase I and glyoxalase II, respectively. The glyoxalase I is a basic protein (pI 7.8), while the glyoxalase II (3 protein bands) is acidic (pI 4.7, 4.8 [prevalent form], and 5.0). The kinetic constants, Km and Vmax, and Ki values for certain inhibitors are reported for both glyoxalase I and glyoxalase II. The glyoxalase enzymes from Aloe vera were compared with reported animal and plant glyoxalases.

Bovine liver mitochondria contain about 10% of the total glyoxalase II activity in the homogenate. Electrophoresis and isoelectric focussing of either crude mitochondrial extract or the purified mitochondrial glyoxalase II resolved the enzyme activity into five forms (pl 6.3, 6.7, 7.1, 7.7, and 7.9). Since bovine liver cytosol contains a single form of glyoxalase II (pl 7.5), at least four forms are exclusively mitochondrial with no counterpart in the cytosol. The relative molecular mass of mitochondrial glyoxalase II is about 23-24 kDa, similar to the cytosolic form. The kinetic constants obtained using S-D-lactoyl, S-acetyl-, S-acetoacetyl-, and S-succinyl-glutathione as substrates are similar to those reported for glyoxalase II from rat liver mitochondria. S-D-Lactoyl- and S-acetoacetyl-glutathione are the best substrates. S-Acetylglutathione is the poorest substrate with respect to both Vmax and Km values.

Glyoxalase II from Candida albicans was purified by affinity chromatography on S-carbobenzoxyglutathione-Affi Gel 10. The enzyme was characterized and compared with the glyoxalases II from animal and plant sources. The relative molecular mass is 29 kDa, and the isoelectric point (pI) is 6.0. The acidic pI value appears to be typical for plant glyoxalase II, in contrast to the uniformly basic glyoxalase II pI values from animals. S-D-Lactoylglutathione and S-acetoacetylglutathione are the best substrates, and S-carbobenzoxyglutathione is the best inhibitor of the yeast enzyme. Glutathione derivatives with a thioether bond are not inhibitory. Glyoxalase II from Candida albicans is compared either with animal and plant enzymes.

S-2-Hydroxyacylglutathione hydrolase (Glyoxalase II) from calf brain has been purified 8333-times compared to 65,000 g supernatant of brain homogenate. The purification procedure employs Affi-Gel blue and preparative isoelectric focussing and offers a suitable method for the preparation of highly purified enzyme. Calf brain Glyoxalase II is a basic protein with a pl of 7.63 determined by isoelectric focusing. An evaluation of the relative molecular mass by gel filtration gave a value of about 23,000. During the purification procedure a constant Km value of about 0.325 mM was observed. A turnover number of 16,100 min-1 was calculated for the purified enzyme.