Publications by authors named "Rotberg N"
Complex formation between the human papilloma virus type 16 E7 protein (HPV-16 E7) and the retinoblastoma growth suppressor protein (RB) is believed to contribute to the process of cellular transformation that leads to cervical carcinoma. Genetic analysis of the HPV-16 E7 protein has shown that the segment of E7 homologous to the conserved region 2 of adenovirus 5 E1A protein is involved in both RB binding and E7-mediated cell transformation. We have previously shown that a peptide colinear with HPV-16 E7 residues 21-29 was able to block immobilized species of E7 from binding to RB protein.
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- Gastrin releasing peptide (GRP) is a 27 amino acid hormone similar to bombesin, and new antagonists were created by modifying its C-terminal structure.
- Two series of these antagonists were developed, showing resistance to degradation in serum while effectively binding to the GRP receptor, with the first series having a binding affinity (IC50) of 6 nM, and the second series being equipotent to native GRP at 2 nM.
- All modified peptides effectively blocked GRP-induced cell growth in mouse fibroblasts and inhibited GRP-stimulated calcium elevation and gastrin release in human cancer cells.
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- The study measured the secondary 15N isotope effects at the N-1 position of 3-acetylpyridine adenine dinucleotide using horse liver alcohol dehydrogenase and yeast formate dehydrogenase with different substrates.
- Previous assumptions suggested that the nicotinamide ring of NAD has a boat conformation with carbonium ion character at C-4 during hydride transfer, which would lead to a noticeable 15N isotope effect.
- The measured kinetic 15N isotope effects for both enzymes were low, indicating that the pyridine ring remains planar during the dehydrogenase reactions, contradicting the earlier proposed deformation mechanism.
The kinetics of chloroperoxidase-catalyzed bromination and chlorination reactions were studied at various halide and hydrogen peroxide concentrations. At very high concentrations, both chloride (KI = 370 mM) and bromide (KI = 150 mM) are competitive substrate inhibitors versus hydrogen peroxide. Results at subinhibitory halide concentrations for bromination reactions (kcat = 4 ms-1, kcat/KPeroxide = 1.
View Article and Find Full Text PDFChloride ion (Cl-) effects on chloroperoxidase (CPO)-catalyzed peroxidation of catechol were used to probe the involvement of Cl- in CPO reactions. High concentrations of Cl- inhibit catechol peroxidation by competing with hydrogen peroxide (KI = 370 mM). However, at lower concentrations, Cl- is a linear competitive activator versus catechol (KDC = 35 mM).
View Article and Find Full Text PDFGastrin releasing peptide (GRP) is a 27-residue peptide hormone which is analogous to the amphibian peptide bombesin. GRP serves a variety of physiological functions and has been implicated as an autocrine factor in the growth regulation of small cell lung cancer cells. We have developed a series of potent GRP antagonists by modification of the COOH terminus of N-acetyl-GRP-20-27.
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