I am very grateful for the honor conferred upon me by your kind invitation to give the first Sobotka Memorial Lecture. I accept with pleasure because it gives me an opportunity to pay my personal tribute to the memory of a most distinguished biochemist who undoubtedly was one of the founders of modern clinical chemistry. I first met Dr. Sobotka at the First International Congress of Clinical Ch...

Lactate dehydrogenase (LD; EC 1.1.1.27) and creatine kinase (CK; EC 2.7.3.2) are widely distributed cytoplasmic enzymes. LD has five and CK has three isoenzymes distributed in different proportions in various tissues. The amounts of LD and CK and the distribution of isoenzymes in different body fluids are not thoroughly characterized. We have measured the total LD and CK concentrations and thei...

Introduction The changes of enzyme activity in the hepatocytes in the course of different liver diseases are reflected by increase of the corresponding enzyme activity in the plasma. For example, the activities of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) correlate with the severity of the condition during cirrhosis. In this study we measured the activity of ADH isoenzymes a...

1. Differentiation of the anodic (LDHi and LDH2) and cathodic (LDHs) isoenzymes of lactate dehydrogenase in human sera can be accomplished by combining variable substrate (lactate or pyruvate) concentrations with specific inhibitors such as urea. 2. One technic useful in the clinical laboratory is based upon a colorimetric assay for total LDH activity in which the oxidation of lactate is couple...

Alkaline phosphatase (EC 3.1.3.1) isoenzymes in serum may be determined by multicomponent analysis of the enzyme activities in the presence of multiple inhibitors. To determine inhibition coefficients of the isoenzymes, we used multiple linear regression analysis to compare alkaline phosphatase activities in the presence of known inhibitors with electrophoretically determined isoenzyme activiti...

We examined the effects of temperature on the activity and steady-state kinetic properties of alkaline phosphatase (EC 3.1.3.1). Purified isoenzymes from human liver, intestine, and placenta were used, as was human serum, and the enzyme from porcine kidney. Phosphatase activity was estimated by two different assay techniques. For all isoenzymes, apparent Michaelis constants for the substrate 4-...

The nucleotide sequence of aroH, the structural gene for the tryptophan-sensitive 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase [DAHPS(Trp)], is presented, and the deduced amino acid sequence of AroH is compared with that of the tyrosine-sensitive (AroF) and phenylalanine-sensitive (AroG) DAHPS isoenzymes. The high degree of sequence similarity among the three isoenzymes strongly indicat...

Serial plasma determinations of the isoenzymes of CPK were performed in all patients (376) admitted to a coronary care unit during a 12-month period with diagnosis of possible acute myocardial infarction. Results were compared with data from other enzyme studies and from the electrocardiogram. An attempt was made to determine the incidence of falsely positive CPK-MB (myocardial-specific form). ...

To determine whether the tissue distribution of glutathione S-transferase (GST) isoenzymes could define the precise nature of renal injury, 13 adult kidneys were studied, using specific antibodies raised against purified isoenzymes. Basic GST stained strongly proximal convoluted tubules and some medullary tubules; acidic GST stained strongly distal convoluted tubules and medullary tubules; neut...