Specific reduction of carboxyl groups in peptides and proteins by diborane

1. The reaction of several peptides and proteins with diborane was studied under different conditions to determine those most suitable for the specific reduction of carboxyl groups. 2. In the reaction of model peptides and the cyclic peptides bacitracin and tyrocidin, reduction at 0 degrees was entirely specific for the carboxyl groups without affecting the peptide bonds. Acid amide residues were not reduced. Some tripeptides showed anomalous results in that the C-terminal residue was quite resistant to reduction. 3. Specific reduction of carboxyl groups was achieved in each of the following proteins: human serum albumin, egg albumin, adult human haemoglobin, sperm-whale apomyoglobin, horse heart cytochrome c and egg-white lysozyme. The C-terminal amino acid was usually reduced. 4. Conditions for specific reduction of all available carboxyl groups are not easily found and may vary from one substance to another. Specific reduction of a limited number of available carboxyl groups may be generally accomplished by reactions at -10 degrees . 5. It is suggested that this chemical modification, which has the advantage of permanence, may be useful in studying the role of carboxyl groups in the conformation of proteins and in the biological properties of peptides and proteins.     

Familiäre 2/C-Translokation: 46,XY t (2p-; Cp+) und 46,XX Cp+

Zusammenfassung Bei einem Patienten mit multiplen Mißbildungen wurde eine Duplikation für die distale Hälfte vom kurzen Arm des Chromosoms 2 und eine Defizienz an einem C-Chromosom gefunden. In der Literatur sind vier Fälle mit ähnlicher Duplikation, jedoch jeweils einer klein n Defizienz am Chromosom 3 beschrieben worden. Ein Vergleich der klinischen Merkmale bei den fünf Patienten zeigt weitgehende Übereinstimmungen. Es wird gefolgert, daß die gleichartige Duplikation für das einheitliche klinische Bild der Patienten verantwortlich ist. Es wurden Chromosomenmessungen, Analysen der Replikationsmuster und Meioseuntersuchungen durchgeführt. Die Genloci für das Ss- und das Rh-System konnten von einer Lokalisierung auf dem duplizierten Segment ausgeschlossen werden.

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2/C translocation in father and daughter: 46,XY t (2p-;Cp+) and 46,XX Cp+

Summary In a patient with multiple anomalies, a duplication comprising the distal half of the short arm of chromosome 2 and a small deficiency of a C-chromosome was found. Four other cases from the literature exhibit a similar duplication combined with a small deficiency each of chromosome 3. Comparison of the clinical pictures of the five patients revealed a conformity in the major features. It is concluded that the duplication is responsible for the uniform appearance of these patients. The studies performed include chromosome measurements, examination of replication patterns and meiosis. The gene loci for the Ss and Rh systems could be excluded from localization on the duplicated segment.

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Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.