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991.
992.
Data from a series of human exposures to carbon monoxide (CO) were analyzed to determine the fit to the theoretical Coburn-Forster-Kane (CFK) equation which describes CO absorption and excretion. The equation was found to predict carboxyhemoglobin (HbCO) saturations for both men and women at exercise rates ranging from sedentary to 300 kpm/min when they were exposed to steady CO concentrations of 50, 100, and 200 ppm for 0.33-5.25 h. Methods for determining values of each of the variables in the CFK equation were collected and a rational, efficient procedure for solving the equation by trial and error was outlined. The CFK equation was then used to prepare a graph, relating HbCO saturation to exposure duration and concentration, and also to describe the effect of several variables on the rate of CO uptake and equilibrium HbCO levels, important considerations in the determination of permissible public, occupational, and experimental exposure to CO. 相似文献
993.
Sequence of an epidermal growth factor-binding protein 总被引:4,自引:0,他引:4
A cDNA clone has been isolated that corresponds to the entire translated region of the mRNA coding for the epidermal growth factor-binding protein type B. The complete nucleotide sequence and the predicted amino acid sequence of the protein were elucidated. The protein sequence was compared to some related serine proteases. This comparison supports the notion that several serine proteases suggested to be involved in the processing of precursors to polypeptide hormones and growth factors are closely related to each other. It appears that these proteases are descendants of a common ancestral gene and thus form a distinct subfamily among the serine proteases. 相似文献
994.
995.
K Früh Y Yang D Arnold J Chambers L Wu J B Waters T Spies P A Peterson 《The Journal of biological chemistry》1992,267(31):22131-22140
The finding that two subunits of the proteasome, LMP2 and LMP7, are encoded in the major histocompatibility complex (MHC) has linked the proteasome which represents a major extralysosomal proteolytic system to the processing of intracellular antigens. Here we describe a second form of the human LMP7 cDNA, LMP7-E2, which has been identified during the characterization of novel genes in the MHC. The analysis of the genome organization of LMP7 revealed that LMP7-E1 and LMP7-E2 arise by alternative exon usage. Using specific antibodies against LMP2 and LMP7, we show that they are co-expressed with class I MHC molecules as well as a putative peptide transporter. The polypeptides encoded by LMP7 and LMP2 undergo proteolytic processing when incorporated into proteasomes, and the LMP7 precursor is derived mainly from LMP7-E2. Furthermore, our data suggest that LMP7 and LMP2 are mutually dependent for their incorporation into the proteasomal complex. 相似文献
996.
997.
A comparative study of the low-temperature magnetic circular dichroism spectra of horse heart metmyoglobin and bovine liver catalase derivatives 总被引:6,自引:0,他引:6
D G Eglinton P M Gadsby G Sievers J Peterson A J Thomson 《Biochimica et biophysica acta》1983,742(3):648-658
The magnetic circular dichroism (MCD) spectra of three horse heart metmyoglobin compounds, the cyanide, azide and hydroxide forms, have been measured in the visible and near infrared spectral regions at temperatures down to 1.5 K. The three compounds are all virtually completely low-spin at low temperatures with ground g factors of decreasing rhombicity in the order CN- greater than N3- greater than OH-. The MCD magnetization curves have been constructed at selected wavelengths throughout the visible and near infrared regions. The curves are independent of wavelength, showing that all the bands studied are x,y polarized and can, moreover, be satisfactorily fitted to the g factors determined by EPR spectroscopy with theoretical expressions (Thomson, A.J. and Johnson, M.K. (1980) Biochem. J. 191, 411-420). This confirms the assignment and polarizations of the near infrared region low-spin ferric haem charge-transfer bands. The energies of these transitions are markedly dependent upon the added axial ligand, ranging from 1595 to 1295, and 1050 nm for the compounds CN-, N3- and OH-. The MCD spectra of bovine liver catalase and its cyanide adduct have been recorded in the Soret, visible and near infrared regions. Catalase is know to have phenolate anion as the proximal ligand of the haem group. The forms of the spectra make an interesting comparison with those of the analogous metmyoglobin derivatives, in which histidine is the proximal ligand. The MCD spectra of catalase at 4.2 K is an example of a fully high-spin haemoprotein. The cyanide compound is completely low-spin at 4.2 K. The near infrared charge-transfer band is at 1300 nm, showing the effect on the energy of this band of changing from imidazole to phenolate ion as the proximal ligand to haem. 相似文献
998.
Ion-exchange displacement chromatography of proteins, using narrow-range carboxymethyldextrans and a new index of affinity 总被引:1,自引:0,他引:1
A new method of characterizing carboxymethyldextrans with respect to their relative affinities for an anion exchanger can be applied not only to pure preparations but also to fractions of a displacement chromatogram in which these polyanions have been used as spacers. This, along with the development of a means of preparing carboxymethyldextrans with narrow ranges of affinity, as contrasted with the very heterogeneous preparations previously used, has greatly facilitated the focusing of resolving power on critical regions of the chromatogram. The effectiveness of this approach is illustrated by the separation of proteins that differ only slightly in affinity, using the genetic variants of beta-lactoglobulin as one model and the numerous components of purified ovalbumin as another. 相似文献
999.
dUDP-GlcNAc, the 2'-deoxyribosyl analogue of UDP-GlcNAc, has been identified in human lymphoid cells treated with the dihydrofolate reductase inhibitor, methotrexate. It was shown previously that elevation of dUTP accompanies the gross expansion in intracellular deoxyuridylate pools that results from the methotrexate-induced block in thymidylate synthetase activity (1). dUDP-GlcNAc presumably is formed from dUTP acting in place of UTP in the normal pathway for formation of UDP-GlcNAc. Neither dUTP nor dUDP-GlcNAc has been detected in untreated cells. Inhibition of thymidylate synthetase by treatment of cells with 5-fluorodeoxyuridine (5-FdUrd) also causes the appearance of dUDP-GlcNAc, and, in addition, 5-FdUDP-GlcNAc, synthesized from 5-FdUTP. The metabolic effects, if any, of these analogues are not known. Synthesis of the analogues may help to limit accumulation of dUTP and 5-FdUTP under circumstances in which the deoxyuridine triphosphatase mechanism is insufficient. 相似文献
1000.
Effect of aging on ventilatory response to exercise and CO2 总被引:2,自引:0,他引:2
Brischetto M. J.; Millman R. P.; Peterson D. D.; Silage D. A.; Pack A. I. 《Journal of applied physiology》1984,56(5):1143-1150