Creatine kinase isoenzyme MB catalytic activities in human serum, determined by ACA ion exchange chromatography and immunoinhibition, differ significantly, the correlation coefficient being 0.88. The reasons for this variation are interference of antibodies with the creatine kinase B subunit in the immunoinhibition assay, nonreproducible elution of creatine kinase isoenzyme MB from the ion exch...

A steady-state kinetic method has been revised for measuring lactate dehydrogenase isoenzyme activities, which relates the inhibition of heart-type isoenzyme activity to the overall isoenzyme composition of the enzyme subunits. The method depends on the pH-dependent formation of an inhibitory ternary complex by the heart-type isoenzyme with NAD+ and pyruvate (if the reaction is measured by NADH...

The X-linked enzyme, glucose-6-phosphate dehydrogenase (G-6-PD) was used as a cellular marker to study the clonal characteristics of human atherosclerotic lesions from females heterozygous for G-6-PD isoenzymes. Portions of uninvolved aortic wall contained both isoenzyme types (A and B), and their isoenzyme patterns were used to establish criteria for polyclonal lesions. Portions of uterine lei...

We compared an alkaline phosphatase (EC 3.1.3.1) isoenzyme from a plasma sample of a patient with carcinoma of the lung, who was suspected of having the Regan-type isoenzyme, with placental serum alkaline phosphatase and with tissue preparations from placenta, liver, bone, and intestine. The placental and Regan phosphatases responded similarly to heat treatment and modification by various inhib...

1. Rat liver and heart major isoenzymes of NADP-isocitrate dehydrogenase have each been purified about 100-fold by a combination of ammonium sulphate fractionation and chromatography on ion-exchange cellulose and their properties compared. 2. The properties were similar in respect of pH, inhibition by Hg(2+) and Michaelis constants for isocitrate and NADP. 3. Some of the properties of the isoen...

A single-blind study involving amniotic-fluid samples from 214 pregnancies of known outcome confirms that an electrophoretically distinct isoenzyme of acetylcholinesterase is associated with fetal open neural tube defects. Furthermore, only one of 13 amniotic-fluid samples with false-positive results for alpha-fetoprotein showed the characteristic isoenzyme, indicating that qualitative acetylch...

The deficiency of the A isoenzyme of beta-hexosaminidase (Hex) produced by different mutations of the gene that codes for the alpha subunit (Tay-Sachs disease) has two variants with enzymological differences: the B variant consists of the absence of Hex A isoenzyme and the B1 variant produces an inactive Hex A isoenzyme for the hydrolysis of the GM2 ganglioside and synthetic substrates with neg...

BACKGROUND Leishmaniasis is endemic in Iran. Different species of Leishmania (L.) parasites are causative agents of this disease. Correct identification of Leishmania species is important for clinical studies, prevention, and control of the diseases. Mix up of Leishmania isolates is possible in the laboratory, so there is need for verification of species for isolates of uncertain identity. Diff...

Two isoenzymes of NADP-linked isocitrate dehydrogenase have been identified in Acinetobacter lwoffi and have been termed isoenzyme-I and isoenzyme-II. The isoenzymes may be separated by ion-exchange chromatography on DEAE-cellulose, by gel filtration on Sephadex G-200, or by zonal ultracentrifugation in a sucrose gradient. Low concentrations of glyoxylate or pyruvate effect considerable stimula...

The MB isoenzyme of creatine kinase (EC 2.7.3.2) may be prepared in vitro by dissociation of the MM and BB dimers into the M and B monomers. These monomers then recombine in a random manner to form all possible combinations-MM, MB, and BBthe presence of which may be detected by chromatography or electrophoresis. Dawson et al. (1) describe this process for animal tissues, while Keutel et a!. (2)...