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Biomedical subjects

S Bajusz

Publications and source records attributed to S Bajusz.

At least 73 records · Page 4Linked to original sources
PubMed1979

A method for designing peptide substrates for proteases. Tripeptidyl-p-nitroanilide substrates for subtilisin Carlsberg.

1. The kinetic parameters of 25 peptidyl-p-nitroanilide substrates were investigated with subtilisin Carlsberg as model enzyme. 2. For a series of 12 substrates, the contribution of various side chains to the affinity constant was computed by regression analysis. From these contributions the sequence of a new and better substrate, N-benzyloxycarbonyl-arginyl-norleucyl-norleucyl-p-nitroanilide (Z-Arg-Nle-Nle-Nan) was predicted. The compound was synthesized and assayed. Its calculated 1/Km value, 43.5 mM-1, was in a good agreement with the value of 40.0 mM-1 that was determined experimentally. 3. On expanding the series to 19 substrates, it was found that the productivity of enzyme-substrate binding is influenced primarily by those subsites which have a significantly greater contribution to the affinity constants than others. 4. The additivity principle applied reasonably well for the contribution of individual side chains to the kinetic parameters. This fact suggests that regression analysis can be used for the prediction of the amino acid sequence of better substrates than those already tested, probably not only for subtilisin but also for other proteolytic enzymes.

Kinetics↗
PubMed1979

Effect of Met-enkephalin and (D-Met2,Pro5)-enkephalinamide on the adenylate cyclase activity of rat brain.

Among opiatelike peptides, stimulatory as well as inhibitory effects are encountered on adenylate cyclase activity. These actions are dependent not only on the investigated brain region but also on the applied peptide. Met-enkephalin stimulates adenylate cyclase activity in the rat brain stem (D-Met2, Pro5)-enkephalinamide and beta-endorphin inhibited it, whereas all three peptides inhibited the activity of cortex. Naloxone antagonized the effects of the applied peptides in the presence of sodium chloride.

Adenylyl Cyclases↗
PubMed1979

Kinetic studies in isolated organs: tools to design analgesic peptides and to analyze their receptor effects.

The opioid activities of peptide and non-peptide narcotics were studied in longitudinal muscle strip of guinea pig ileum (GPI) and in mouse vas deferens (MVD). The comparison of agonist activities of peptides found in GPI and MVD offered the opportunity to predict the presence but not the magnitude of potential analgesic activity. The kinetics of the antagonism between naltrexone and different types of agonists were also determined in these systems. Using C-6 epimers of naltrexone, it was found that the site of opiate receptors recognizing the information provided by the C-6 substituent of naltrexone are different in GPI and MVD.

Analgesics, Opioid↗
PubMed1978

Prolactin and growth hormone releasing activity of [D-Met2, Pro5]-enkephalinamide in the rat after systemic administration.

The growth hormone (GH) and prolactin releasing (PRL) activity of [D-Met2, Pro5]-enkephalinamide (EKNH2). an opioid peptide analog with higher opiate agonist activity that morphine, was compared in the unanesthetized male rat to those of equimolar doses of morphine upon systemic injection. EKNH2 proved to be a higher PRL, but not GH, releaser than the opiate alkaloid.

Animals↗
PubMed1978

Inhibition of thrombin and trypsin by tripeptide aldehydes.

Inhibitory effects of certain tripeptide aldehydes on both thrombin and trypsin have been found to be strongly substrate-dependent. These compounds should therefore be considered as inhibitors of the particular proteolytic reaction for which they had been designed rather than real enzyme inhibitors, i.e. protein or polypeptide proteinase inhibitors of natural origin.

Aldehydes↗
PubMed1978

In vivo antagonism by naloxone of morphine, beta-endorphin and a synthetic enkephalin analog.

The in vivo equivalent of pA2 values were determined in rat tail-flick and mouse hot-plate tests for naloxone against morphine, beta-endorphin and a synthetic enkephalin analog, (D-Met2,Pro5)-enkephalinamide, as analgesics. In mice the apparent pA2 value of naloxone against morphine (6.86) was similar to that found by previously and essentially the same values were obtained against the opioid peptides, indicating homogenous receptor population for the analgesics studied. In rats the pA2 of naloxone against morphine (7.17) was lower than against either beta-endorphin (7.55) or (D-Met2,Pro5)-enkephalinamide (7.51), warning that in rats such a homogeneity of the "analgesic" receptor population as was observed for mice may not exist.

Animals↗
PubMed1977

Preparation and characterization of Ng-mono-, di- and trimethylated arginines.

A simple procedure is described for the synthesis of N-guanidino methylated ariginines. The yields of all methylarginines exceed those obtained by earlier procedures. Trimethylarginine - an amino acid not found in natural sources - has also been synthesized with this technique. Studies with arginine specific dicarbonyl reagents showed that methylation of guanidino-groups decreases the reactivity of methyl-arginines, only monomethylarginine reacting at a rate comparable to that of arginine.

Arginine↗