Immunoreactive glucagon in the vascular walls of the rat

We detected immunohistochemically immunoreactive glucagon (IRG) in the smooth muscle of blood vessels and the myoepithelial cell of sweat glands of rats using two antisera against pancreatic glucagon; OAL-123 and 30K. The content of IRG in the blood vessels was found to be 320-1, 270 pg per g wet tissue weight. Filtration of the extracted IRG through a Bio Gel P-30 column yielded a single peak of IRG at 3,500 daltons, the same elution volume of pancreatic glucagon. These findings suggest that the blood vessels of the rats is one of the extrapancreatic sources of IRG in plasma, although physiological role of the IRG is not known.     

Non-cognizable ribonucleotide, 2''AMP, binds to a mutant ribonuclease T1 (Y45W) at a new base-binding site but not at the guanine-recognition site.

Complex of a mutant ribonuclease T₁ (Y4SW) with a non-cognizable ribonucleotide, 2′AMP, has been determined and refined by X-ray diffraction at 1.7 Å resolution. The 2′AMP molecule locates at a new base-binding site which is remote from the guanine-recognition site, where 2′GMP was found to be bound. The nucleotide adopts the anti conformation of the glycosidic bond and C3′-exo sugar pucker. There exists a single hydrogen bond between the adenine base and the enzyme, and, therefore, the site found is apparently a non-specific binding site. The results indicate that the binding of 2′AMP to the guanine-recognition site is weaker than that to the new binding site.     

A quantitative structure-activity relationship study for structurally diverse HIV-1 protease inhibitors: contribution of conformational flexibility to inhibitory activity

In this study, we investigated by linear regression model the SAR data of the 15 HIV-1 protease inhibitors possessing structurally diverse scaffolds. First, a regression model was developed only using the enzyme-inhibitor interaction energy as a term of the model, but did not provide a good correlation with the inhibitory activity (R² = 0.580 and Q² = 0.500). Then, we focused on the conformational flexibility of the inhibitors which may represent the diversity of the inhibitors, and added two conformational parameters into the model, respectively: the number of rotatable bonds of ligands (ΔSrot) and the distortion energy of ligands (ΔElig). The regression model by adding ΔElig successfully improved the quality of the model (R² = 0.771 and Q² = 0.713) while the model with ΔSrot was unsuccessful. The prediction for a training inhibitor by the ΔElig model also showed good agreement with experimental activity. These results suggest that the conformational flexibility of HIV-1 protease inhibitors directly contributes to the enzyme inhibition.     

Rapamycin induces binding activity to the terminal oligopyrimidine tract of ribosomal protein mRNA in rats

Cathepsin G, elastase, and proteinase 3 are serine proteinases released by activated neutrophils. Cathepsin G can cleave angiotensinogen to release angiotensin II, but this activity has not been previously reported for elastase or proteinase 3. In this study we show that elastase and proteinase 3 can release angiotensin I from angiotensinogen and release angiotensin II from angiotensin I and angiotensinogen. The relative order of potency in releasing angiotensin II by the three proteinases at equivalent concentrations is cathepsin G > elastase > proteinase 3. When all three proteinases are used together, the release of angiotensin II is greater than the sum of the release when each proteinase is used individually. Cathepsin G and elastase can also degrade angiotensin II, reactions which might be important in regulating the activity of angiotensin II. The release and degradation of angiotensin II by the neutrophil proteinases are reactions which could play a role in the local inflammatory response and wound healing.     

Receptors for recombinant feline interferon-omega in hemocytes of the Japanese pearl oyster Pinctada fucata martensii

In a previous study we determined that administration of recombinant feline interferon-omega (rFeIFN-omega) could protect Japanese pearl oysters Pinctada fucata martensii from akoya-virus infection. Our results suggested that rFeIFN-omega enhanced the potential of agranulocytes to phagocytize necrotic cells and to produce collagen fibers that repair the lesions caused by the akoya-virus. In the present study, using an indirect immunofluorescence technique with an anti-rFeIFN-omega rabbit serum, we examined whether hemocytes bear receptors that bind rFeIFN-omega. rFeIFN-omega receptors were present on agranulocytes and bound rFeIFN-omega, and appeared as green fluorescent spots in the cytoplasm under a fluorescent microscope. Around 56% of agranulocytes in Japanese pearl oysters bore the rFeIFN-omega receptors.     

Multiple four-stranded conformations of human telomere sequence d(CCCTAA) in solution

By detailed NMR analysis of a human telomere repeating unit, d(CCCTAA), we have found that three distinct tetramers, each of which consists of four symmetric single-strands, slowly exchange in a slightly acidic solution. Our new finding is a novel i-motif topology (T-form) where T4 is intercalated between C1 and C2 of the other duplex. The other two tetramers have a topology where C1 is intercalated between C2 and C3 of the other parallel duplex, resulting in the non-stacking T4 residues (R-form), and a topology where C1 is stacked between C3 and T4 of the other duplex (S-form). From the NMR denaturation profile, the R-form is the most stable of the three structures in the temperature range of 15–50°C, the S-form the second and the T-form the least stable. The thermodynamic parameters indicate that the T-form is the most enthalpically driven and entropically opposed, and its population is increased with decreasing temperature. The T-form structure determined by restrained molecular dynamics calculation suggests that inter-strand van der Waals contacts in the narrow grooves should contribute to the enthalpic stabilization of the T-form.