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Biomedical subjects

N A Guzman

Publications and source records attributed to N A Guzman.

At least 37 records · Page 2Linked to original sources

Purification and characterization of a peptide from the carboxy-terminal region of chick tendon procollagen type I.

A disulfide-bonded peptide with a molecular weight of about 100 000 was isolated from the medium of cultured chick embryo tendons. It was shown to be a trimer with two types of subunits in a 2:1 ratio, and tryptic fingerprinting and immunological evidence indicated that it was derived from the carboxy-terminal-precursor-specific region of procollagen. Amino acid analysis after reduction and alkylation indicated that the trimer contains about 30 residues of half-cystine involved in intrachain as well as interchain disulfide bonding. The interchain bonds could be reduced and alkylated under nondenaturing conditions. Carbohydrate analysis showed that each of the three peptide chains in the trimer contains about two residues of N-acetylglucosamine and about ten residues of mannose. This suggests the presence of one or two oligosaccharide units per chain.

Acetylglucosamine↗

Collagen diseases and the biosynthesis of collagen.

Increasing knowledge concerning the molecular structure of collagen and the steps involved in its biosynthesis provides the basis for a new look at the collagen diseases. Some, like the Ehlers-Danlos syndrome, are now known to be the expression of primary molecular defects; others, such as scurvy and scleroderma, appear to be secondary to some process that disrupts normal controls over collagen synthesis or deposition.

Amino Acid Sequence↗

Monitoring the purity of a synthetic peptide by capillary electrophoresis: utilization of an on-line preconcentration method for improved separation and detection sensitivity.

To date, there has been a considerable amount of interest and success in the pharmaceutical industry in the discovery of drug targets and diagnostics utilizing peptides. The success of peptide pharmaceuticals has, however, been accompanied by some failures, both prior to entry and in the clinic. Progress has been made in various areas to improve the effectiveness of the final drug product. One major advance has been in the area of peptide synthesis and control of the purity of the peptide of interest. Recent advances in analytical instrumentation, including advances in capillary electrophoresis, have had a great impact on the ability to separate and detect low quantities of impurities and degradation products during the synthesis of a peptide drug. In this work, affinity capillary electrophoresis (ACE) was developed for the identification and characterization of a chemically synthesized peptide fragment of a snake toxin called fasciculin. The affinity capillary electrophoresis technology utilized in this study employed two powerful techniques coupled on-line for the direct and rapid determination of analytes in simple and complex matrices. The first technique, aimed for the nonselective extraction and concentration of one or more analytes of interest, utilizes a solid-phase analyte concentrator device. The second technique, capillary electrophoresis, is used for the high-resolution analytical separation of the purified and concentrated target analyte(s), after elution from an analyte concentrator device. The on-line preconcentration step has proved valuable in terms of improving separation conditions as well as enhancing detection sensitivity values for the peptide fragment with a sensitivity increase ranging from 100- to 10,000-fold. Different types of analyte concentrator devices and a few binding-desorption conditions were tested. Bare and internal-wall-coated fused-silica capillaries were used. Comparative performance with HPLC in terms of selectivity and sensitivity is also discussed.

Chromatography, High Pressure Liquid↗

A comparative study of fish species identification by gel isoelectrofocusing two-dimensional gel electrophoresis, and capillary zone electrophoresis.

A comparative study of fish species identification was accomplished using three different electrophoretic techniques. Sarcoplasmic proteins were extracted from three related fish species and subjected to gel isoelectrofocusing (IEF), two-dimensional polyacrylamide gel electrophoresis (2D-PAGE), and capillary zone electrophoresis (CZE). The fish species--Genypterus chilensis, Genypterus blacodes, and Genypterus maculatus--were from the Ophidiidae family. The three electrophoretic techniques provided suitable fish species identification. Nevertheless, CZE demonstrated several advantages over the other two conventional techniques. Some of the benefits include the use of small amounts of reagents; short separation times, permitting fast comparative analysis; data reproducibility; and ease with which the technique is performed.

Animals↗

Analysis of brain neuropeptides by capillary electrophoresis: determination of luteinizing hormone-releasing hormone from ovine hypothalamus.

The use of capillary electrophoresis to analyze in vivo release of luteinizing hormone-releasing hormone from the ewe median eminence and tissue content of luteinizing hormone-releasing hormone from discrete brain areas (within and immediately adjacent to the median eminence) is described. Results were compared with those obtained with a specific luteinizing hormone-releasing hormone radioimmunoassay. In vivo release samples were obtained by a push-pull cannula procedure. The exact position of the median eminence in each animal was determined from lateral roentgenographs after infusion of a radiopaque dye into the third ventricle. Each ewe median eminence was perfused with an artificial cerebrospinal fluid solution and sampled at 20-min intervals. Brain tissues for luteinizing hormone-releasing hormone content were obtained after each animal was killed. Samples were either analyzed by capillary electrophoresis and UV detection at 210 nm or assayed with a specific luteinizing hormone-releasing hormone radioimmunoassay. Tissue homogenate content and release samples had several peaks resolved by capillary electrophoresis and UV detection. Luteinizing hormone-releasing hormone was identified as one of these peaks. Luteinizing hormone-releasing hormone was also shown to be present in these samples when evaluated by radioimmunoassay. A good correlation between capillary electrophoresis and radioimmunoassay was observed for luteinizing hormone-releasing hormone content values obtained from discrete hypothalamic areas.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Dr. Csaba Horváth.

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Chemistry, Analytic↗

Dr. Salvatore Fanali.

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Chemistry, Analytic↗

Dr. Richard D. Smith.

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Chemistry, Analytic↗

Dr. Susumu Honda.

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Chemistry, Analytic↗

Dr. Kiyokatsu Jinno.

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Electrophoresis, Capillary↗