Ratio of the antiproliferative action of interferon to the degree of purity of the preparation

The antiproliferative (AP) action of human leukocytic interferon (HLI) of varying degrees of purification was studied and compared in cultures of human cells differing in interferon sensitivity. The concentrated and purified preparations of HLI suppressed the incorporation of 3H-thymidine and mitotic activities of the cultures sensitive to HLI of the cells, affecting, but insignificantly, the proliferation of the resistant cell culture. Poorly purified HLI suppressed the proliferation of both cell types. This indicates that native HLI contains impurities that have an AP action and exerts no antiviral activity.     

Study of the complex formation between alpha- and beta- forms of NAD-kinase and glutamate dehydrogenase and the effect of metabolites on enzyme interaction

The alpha- and beta-forms of rabbit liver NAD kinase were found to differ significantly in terms of their ability to form complexes with glutamate dehydrogenase. The beta-form of the enzyme was shown to form a more stable complex with glutamate dehydrogenase (Kd = 1.5.10(-8) M), whereas the Kd value for the alpha-form is 2.9.10(-7) M. Using two independent methods, it was shown that in the absence of effectors 40% of the beta-form of NAD kinase and up to 20% of the alpha-form are bound to glutamate dehydrogenase. The substrates of NAD kinase markedly activate the complex formation only in the case of the alpha-form of the enzyme. The time needed for this process is also reduced in the presence of the substrates.     

Comparative analysis of analgesic activities of dermorphin, [DPro<Superscript>6</Superscript>]-dermorphin,and their C-terminal tripeptides

Analgesic activities of dermorphin (DM), [DPro⁶]-DM, and their C-terminal tripeptides were comparatively studied. Analgesic activity was evaluated in tail flick, hot plate, tail pinch, formalin, and acetic acid writhing tests describing different levels of organization of pain sensitivity. Intraperitoneal administration of the peptides decreased the pain threshold in all these tests. The C-terminal tripeptides DM_5–7 and [DPro⁶]-DM_5–7 demonstrated analgesics activity comparable or sometimes higher than that of the full-length molecules. The effect of DM, [DPro⁶]-DM, and C-terminals fragments DM_5–7 and [DPro⁶]-DM_5–7 decreased after co-administration with naloxone, which points to the opioid nature of analgesic activity of the peptides.