PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Spectrophotometry, Ultraviolet”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 469 records · Page 26Linked to original sources
PubMed1985

Heme-linked spectral changes of the protein moiety of hemoproteins in the near ultraviolet region.

Spectral changes of hemoproteins in the near ultraviolet region on binding to a ligand and on oxidation-reduction of the heme-iron were studied by computer-controlled spectrophotometry. Near ultraviolet difference spectra between the low spin and high spin forms of ferric hemoproteins were classified into three groups: Those showing two absorption peaks having maxima at around 285 and 295 nm, those showing a peak at around 275 nm, and those showing a peak at around 300 nm. No corresponding absorption peak was observed with model heme complexes of low molecular weight. The intensity of the peak in cyanide difference spectra of catalase and horseradish peroxidase in the near ultraviolet region was dependent on the concentration of added cyanide and paralleled the intensity of the spectral changes in the Soret region. The spectral changes in both the near ultraviolet and Soret regions developed within 6 ms after the addition of cyanide. Difference spectra between the reduced and oxidized forms of cytochrome c, cytochrome oxidase-cyanide complex, hemoglobin, and lactoperoxidase-cyanide complex showed a characteristic peak at around 285-290 nm. Various difference spectra of hemoglobin in the near ultraviolet region were also measured. The observed positions, shapes, combinations, and relative intensities of the peaks were compared with those of solvent perturbation difference spectra and pH difference spectra of proteins and aromatic amino acids and also with the diacetylchitobiose-induced difference spectrum of lysozyme. The kinds of aromatic amino acid residues possibly responsible for the observed difference peaks were discussed on the basis of the results of the comparison. Based on the results obtained, the common occurrence of a heme-linked functional response of the hemoprotein conformation was suggested.

Animals↗
PubMed1965

METHODS FOR AUTOMATIC NUCLEOTIDE-SEQUENCE ANALYSIS. MULTICOMPONENT SPECTROPHOTOMETRIC ANALYSIS OF MIXTURES OF NUCLEIC ACID COMPONENTS BY A LEAST-SQUARES PROCEDURE.

1. A theoretical analysis of the errors in multicomponent spectrophotometric analysis of nucleoside mixtures, by a least-squares procedure, has been made to obtain an expression for the error coefficient, relating the error in calculated concentration to the error in extinction measurements. 2. The error coefficients, which depend only on the ;library' of spectra used to fit the experimental curves, have been computed for a number of ;libraries' containing the following nucleosides found in s-RNA: adenosine, guanosine, cytidine, uridine, 5-ribosyluracil, 7-methylguanosine, 6-dimethylaminopurine riboside, 6-methylaminopurine riboside and thymine riboside. 3. The error coefficients have been used to determine the best conditions for maximum accuracy in the determination of the compositions of nucleoside mixtures. 4. Experimental determinations of the compositions of nucleoside mixtures have been made and the errors found to be consistent with those predicted by the theoretical analysis. 5. It has been demonstrated that, with certain precautions, the multicomponent spectrophotometric method described is suitable as a basis for automatic nucleotide-composition analysis of oligonucleotides containing nine nucleotides. Used in conjunction with continuous chromatography and flow chemical techniques, this method can be applied to the study of the sequence of s-RNA.

Adenine↗
PubMed1987

Reversed-phase high-performance liquid chromatographic separation and electrochemical detection of retinol and its isomers.

Baseline separation of the isomers of retinol using reversed-phase high-performance liquid chromatography (HPLC) in less than 30 min is presented. A new approach to the detection of retinol using electrochemical detection is developed. The oxidative electrochemistry of retinol is studied at a glassy-carbon electrode using coulometry, ultraviolet-visible spectrophotometry and HPLC. Amperometric detection in HPLC for retinol provided a linear response from 0 to 1.5 micrograms/ml and a detection limit of 4.1 ng/ml. Electrochemical detection was compared to ultraviolet-visible absorbance detection for the determination of retinol in human serum extracts. Good agreement is found for the results obtained with the two detectors.

Chromatography, High Pressure Liquid↗