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An IR spectroscopic study was carried out at room temperature for Human Serum albumin (HSA) glycated with fructose and glucose and inhibited with acetylsalicylic acid. The glycation process was carried out in our laboratory by a conventional method to confirm earlier reported observation of the effect of glycation on the intensity variation of the IR spectra, particularly, in the range 1500 cm-1 to 1700 cm-1 and around 3300 cm-1. IR spectra reveal that the effects of glycation of HSA by fructose are more intense than with glucose, which is the expected. Bovine serum albumin was also glycated using Glucose-6-phosphate disodium salt, and gamma-globulin was glycate with glucose, As expected, the glycation process was more intense with glucose-t-phosphate disodium salt. Acetyl salicylic acid was also used and its inhibitor effects could be observed in both cases, with glucose and with glucose-6-phosphate disodium salt even though, to a smaller extent with the latter. This is consistent with the earlier data and is explained on the basis of the attachment of macromolecules to (epsilon) -NH2 groups of lysines. The experimental results confirm that acetylsalicylic acid, indeed, acts as an inhibitor by acetylation of the (epsilon) -NG2 group where the sugars are supposed to be attached.

Detection of nonenzymatic glycated proteins is a very significant feature in diabetes, aging and related diseases, therefore we have carried out an FTIR spectroscopic study for glycated and native proteins such as (gamma) -globulin, human serum albumin. For this purpose, commercially available proteins were glycated by a usual procedure and their FTIR spectra were recorded together with that of the native ones. In order to follow the changes in time, (gamma) -globulin was glycated during 1, 2, 3, 5 and 8 weeks and their spectra were recorded. Direct verification was obtained by examining a model unit where the -NH2 group was attached to glucose. The spectrum shows a strong peak at 3500 cm-1 confirming the observed variation in time dependent spectra. The general features of the spectra are very similar and there was no additional structure or change in the peaks. This is understandable as not all the lysine residues are glycated, only a small fraction. Glucose is attached to the (epsilon) -amino group of lysine to form Amadori products, and therefore, the vibrational modes corresponding to the (epsilon) -NH2 unit of lysine are expected to be altered. This region exactly lies in the Amide I region of protein structure. Careful investigation of this part, indeed, shows a complex structure originated from alternations of -NH2 group. Thus, the present investigation indicates that an optical approach could be a rapid and effective method to identify the nonenzymatic glycation process.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Albumin is an important protein and its glycated form increases in diabetes mellitus and is partly responsible for the age related phenomena. We have, therefore, investigated the optical absorption and fluorescence spectra of glycated albumin along with a kinetic study by means of a proteolytic reaction. For this purpose, albumin was glycated by a conventional method and the optical absorption spectra were recorded for both the glycated and the native forms, from 240 nm to 400 nm and found that they were dominated by a strong peak at 280 nm which was followed by a long tail up to 300 nm for the native and 400 nm for the glycated protein. Non tryptophane fluorescence spectra of both glycated and native albumins in solid form were investigated and it was found that the general features of both spectra are similar. The spectra are dominated by a weak peak located at 450 nm and an intense broad peak at 550 nm. This peak is followed by a shoulder at 625 nm and then a long tail up to 800 nm. One of the major effects of glycation in this investigation is in their physical forms. Native albumin has a crystalline form while the glycated one has a conglomerate form. This effect can be easily visualized when the sample is examined with the help of a fluorescence microscope. This result is in accordance with the data obtained from electron microscopy. Thus, this quick and direct approach could identify the presence of the glycated protein and could provide information on the pathology of diabetes art an early stage.

Spectral investigations of absorbance in deep ultra-violet region (from 200 nm to 350 nm) of (STM) was carried out for different pH values. On the high energy side the peak is located at 195 nm which is generally attributed to peptide bonds. This peak, as expected, does not show any shift with pH value (4.3 to 10.8). A rather broad peak is spread in the region from 200 nm to 240 nm which could be the superposition of the peaks corresponding to the absorption due to (alpha) helix and (beta) structure. This peak shows a red shift as pH value increases. The same hormone was glycated by a conventional method and the process was estimated with the absorption spectra. The results are discussed in the light of nonenzymatic glycation. It was found that glycation mucus somatotropin resistant towards the denaturation process.

A conventional collinear laser induced fluorescence detection system for capillary electrophoresis was modified by replacing a GaAs photomultiplier by a Charge coupled Device which was operated at liquid nitrogen temperature. This permits longer exposure time to collect the weak radiation and hence extends the limit of detection and spectral analysis of lower concentration of biological active molecules. Using the above technique, and passing the solution through a capillary of 20 micrometers inside diameter, we have recorded fluorescence spectra of biological important molecules such as Arginine, Glutamate and Glutamine; all of them were derivatized with Fluorescein Isothiocyanate (FITC) isomer I. Spectra of FITC as a function of the pH were examined to lower the detection limit. The concentration of the molecules was as low as 10 -14 M. All the spectra recorded lied in the expected region (510 nm to 550 nm) and showed considerable similarity. The spectrum of low concentration of molecules provides significant information as the intensity of intra-molecular interaction is reduced. The recorded spectra gave information about the distribution of vibrational states near S 0 and S 1 levels.

Recently, much interest has been created in laser driven chemical reactions and their application towards photodeposition of thin films of metals on semiconducting substrates. The next logical step is to verify the capability of this technique in making adequate electrical contacts for microelectronic fabrications and for circuit writing. Some work in this direction has been reported for Iron and Tungsten. However, deposition of gold has not been reported so far, even though it is very significant from the technological point of view. Therefore, we are proposing here a method for photodeposition of gold.this pupose, Pyridine gold (III) trichloride was found to be adequated and it was prepared by a conventional method, then dried under vacuum for 48 hours. A concentrated solution was made by dissolving it in Dimethyl sulfoxide. A tiny drop of it was put on the substrate and exposed to radiation 488 nm, obtained from an argon ion laser. The time of photodeposition depends upon the power of the beam; for 2 watt/mm2 and for four to six minutes of continuous exposure, good, low noise, reliable and nearly ohmic contacts were obtained.The method is found to be suitable for both conventional and non conventional semiconductors such as ZnTe, doped and undoped ZnSe, and diluted magnetic semiconductors such as Zn1−xMnxSe for which normally used methods are not applicable. The present technique can also be extended to the hiqh Tc superconductor YBa2Cu3O7. The possible mechanism of photodeposition is also discussed.

Procedures are described for converting primary amines into their well-crystalline trichloroacetyl-derivatives by treatment with hexachloroacetone under mild conditions. Although secondary aromatic N-methylamines are unaffected by hexachloroacetone, saturated heterocyclic amines react vigorously.A mechanistic study using 2-amino-4-t-butylthiazole showed that the reaction is first order in hexachloroacetone, second order in amine, and base-catalysed; there is no appreciable kinetic isotope (H/D) effect nor accumulation of intermediates during the reaction. A sequence which accommodates these results is suggested.