The thermal effects of Nd:YAG, argon, and CO2 laser beams are observed on enamel, dentin, and dental pulp by means of computerized infrared thermography and thermocouple. This study shows that the Nd:YAG laser beam deeply diffuses through the enamel and dentin to the pulp. The argon laser effects are inconsistent depending on whether the enamel surface is cleaned, but after cleaning, the superficial and deep temperatures are low. With the CO2 laser, the enamel and dentin surfaces reach very high temperatures, but only low temperatures are measured in the pulp chamber.
The globin of sheep heart myoglobin was fircit cleaved by cyanogen bromide and the resulting fragments were fractionated by gel filtration and preparative paper electrochromatography ; each fragment was submitted to endopeptidase digestion and the complete amino acid sequence has been determined. The intact globin and the median cyanogen bromide peptide were analysed by the protein sequanator (Edman). This ana,lysis confirmed the sequence of the first 46N-terminal residues of the intact globin and established the sequence of the first 39 N-terminal residues of the median cyanogen bromide peptide.Between sheep and beef myoglobin six differences over 153 residues can be noticed; among the six amino acid replacements, two correspond to the exchange of two bases and four to the exchange of one base in the coding triplets. show that the phylogenetic difference between two species is to some extent quantitatively reflected by the number of differences between amino acid residues in two homologous proteins. Therefore, the experimental procedure already applied to beef heart myoglobin was used for sheep heart myoglobin, with slight modifications, due to the presence of one more residue of methionine in sheep myoglobin [9]. Analysis by Edman's protein sequenator was also used to confirm the sequence of the first 46N-terminal residues and to overcome the difficulties raised by the three tryptic insoluble cores in the intact protein.The intact globin was first digested by trypsin; the tryptic digest was fractionated by ion-exchange chromatography. The characterization of 17 peptides has been reported elsewhere [9]: they account for about two thirds of the molecule; the last third is represented by three insoluble fractions. To complete the sequence, cyanogen bromide was successfully used to cleave the globin into soluble peptides. These fragments were fractionated by Sephadex G-75 chromatography. Three fractions were obtained : peptides N, MI and (M2 + C). These two last peptides were separated by paper electrochromatography.The peptide N represents the N-terminal segment, peptide C corresponds to the C-terminal segment, whereas peptides M1 and M2 represent the median segments. From the tryptic digest of peptide N and from the chymotryptic digest of peptide MI it was possible t o isolate soluble peptides corresponding to the three insoluble cores (1-16, 64-77, 103-115). Peptides M2 and C overlap perfectly the sequence from the 132nd to the 142nd residue, and from the 143rd to the 153rd residue, which were determined by the characterization of tryptic peptides.The analysis of the intact globin by Edman's protein sequenator made the work easier and confirmed previous results : the N-terminal sequence (residues 1 -46), including the first tryptic insoluble core, was determined. By the same method the N-terminal sequence of peptide M i (residue 56-94), including the second tryptic insoluble core, was also established. EXPERIMENTAL PROCEDURE Preparation of Denatured GlobinOvine myoglobin was obtained by ammonium sulfate fractio...
Raman and resonance Raman spectra of plasma lipoproteins +/- malondialdehyde were studied at concentrations which block the normal receptor-mediated uptake by cells. The strong resonance Raman bands at about 1010, 1162 and 1530 cm-1, due to the presence of carotenoids in the lipoproteins, are envisaged as structural probes. High resolution resonance Raman spectra of the 1500-1600 cm-1 region reveal multiple features suggesting the coexistence of several structural populations of beta-carotene whose precise assignment is complex. When plasma lipoproteins are reacted with malondialdehyde, a complex change occurs in the resonance Raman banding of beta-carotene in the 1500-1600 cm-1 region. Malonaldehyde (MDA) also modifies the acoustical region (70-200 cm-1 of low density lipoprotein (LDL) lipids. We suggest that malondialdehyde association with plasma lipoproteins alters the lipid structure via apoprotein or apoprotein/lipid associations.
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