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By using the radioactively labeled 1,4-dihydropyridine (DHP) probe, [3H]PMD, we have demonstrated that cultured human embryonic fibroblasts grown at a low density in Eagle's medium supplemented with serum contain a single class of non-interacting DHP binding sites (Bmax, 1.2 +/- 0.3 pmol/10(6) cells; Kd, 3.9 nM). After inhibition of the DHP receptor(More)
The rate constants and Km for the hydrolysis of the optically active nonglycosidic analogues of the CpA and C greater than p catalysed by RNase A and RNase BS-I were measured. The rate of hydrolysis of the model substrates in 10(5) and 10(3) slower that for the appropriate dinucleoside phosphate and nucleoside cyclophosphate. However, substitution of the(More)
We have studied the spectral properties of RNAase A containing a phosphopyridoxyl residue at the epsilon-NH2 group of Lys-7 or Lys-14. The overall conformations of the native and modified enzymes were shown to be rather similar. All three proteins have similar circular dichroism spectra within the 220-300-nm region, and similar thermal transition(More)
The mechanisms of regulation of cyclic AMP phosphodiesterases were studied using the cytoplasmic fraction of PC-12 cells sensitive to the action of nerve growth factor. The cells contain phosphodiesterases of two types. One of them possesses a high affinity for cyclic AMP (Km = 2.46 mM), whereas the other has the affinity by an order worse (Km = 37.1 mM).(More)
Nerve growth factor (NGF) is a protein which maintains the vital activity of sympathetic and sensory neurons and is involved in the differentiation of various tissues, rising from cells of the neural crest [3]. Cells of certain neurogenic tumors, such as neuroblastomas, pheochromocytomas, and melanomas [2, 4, 9] preserve receptors for NGF on their surface,(More)
Five Hybridoma clones producing monoclonal antibodies (MAT) to bovine nerve growth factor (NGF) were developed. The biological effects of antibodies were studied: the influence of MAT on neurit outgrowth induced by NGF in rat pheochromocytoma PC12 or spinal chicken ganglia was investigated. MAT fell into two groups. Two of them inhibited neurit induction by(More)
Isotermic unfolding of ribonuclease A, phosphopyridoxyl-8Lys41-RNAase A and complexes of the enzyme with cytidine, 2'-CMP, 3'-CMP, 3'-AMP and with the phosphoric ester of 1-(omega-oxypropyl)-cytosine in presence of urea has been studied. The stabilization of the protein structure resulting from the complex formation was shown to be determined by the ligand(More)
The physico-chemical properties have been studied of RNase A selectively modified at the E-NH2-group of Lys-7 and Lys-41 with pyridoxal-P. Modification did not affect conformational stability of the protein globule, thus all changes in the molecule of the modified RNase A were localised around the alkylated Lys residue. In the both cases pyridoxyl-P. The(More)