Carlsberg Research Communications 

About: Carlsberg Research Communications is an academic journal. The journal publishes majorly in the area(s): Peptide sequence & Amino acid. It has an ISSN identifier of 0105-1938. Over the lifetime, 458 publications have been published receiving 16651 citations.

Determination ofD-amino acids. II. Use of a bifunctional reagent, 1,5-difluoro-2,4-dinitrobenzene

Abstract: 1-fluoro-2,4-dinitrophenyl-5-l-alanine amide has been synthesized in high yield (76%) from 1,5-difluoro-2,4-dinitrobenzene andl-Ala-NH2. This compound contains a reactive fluorine atom which can be used for the reaction with a mixture ofl- andd-amino acids. The resulting diastereomers which are obtained in quantitative yield can be separated and estimated by HPLC. With the five amino acids studied (Ala, Asp, Glu, Met and Phe),l-diastereomers were eluted from the reverse-phase column befored-diastereomers. This behavior can be explained by a stronger intramolecular hydrogen bonding in the latter diastereomer. When artificial mixtures of the five amino acids containing known proportions ofl- andd-isomers were derivatized with the reagent and the reaction products analyzed by HPLC, it was possible to determine the relative content of each isomer in nanomole range.

Somatic hybrid plants of potato and tomato regenerated from fused protoplasts

Abstract: Mesophyll protoplasts of Lycopersicon esculentum Mill. var. cerasiforme (Dunal) Alef, mutant yellow green 6, Rick and protoplasts of a liquid callus culture of the dihaploid strain HH258 of Solanum tuberosum L. were prepared and many fusion products were visible after the protoplasts were incubated together first in the presence of polyethylene glycol and then with a high Ca2+ ion concentration. The protoplasts were transferred to a rich medium and the resultant calli were cultured. Some calli regenerated normal green shoots which were transferred to soil or grafted onto a tomato stock. The subunit polypeptide pattern of ribulose 1,5-bisphosphate carboxylase prepared from leaf material of four regenerated plants was analyzed by isoelectric focusing. The ribulose bisphosphate carboxylase enzyme oligomer in the four plants contained the small subunit products resulting from the expression of both tomato and potato nuclear genes proving these plants to be somatic hybrids between tomato and potato. In three of the four plants the large subunit polypeptides and hence the functional chloroplast DNA were from tomato whereas in the fourth the large subunit and therefore the chloroplast DNA was derived from potato. The plant material was insufficient to establish the chromosome numbers precisely, however counts close to 50 which is near to the expected 48 were obtained for three of the hybrids whereas in the fourth a number close to 72 was observed. In the absence of a selection system against the potato parent, the analysis of ribulose bisphosphate carboxylase provides a convenient marker to demonstrate the hybrid nature of the plants.

Chlorophyll-proteins of thylakoids from wild-type and mutants of barley (Hordeum vulgare L.)

Abstract: A sodium dodecyl sulphate-polyacrylamide gel electrophoresis system is described that resolves wild-type barley thylakoid components into ten chlorophyll-containing bands, plus free chlorophyll. Many of these bands have been characterised with respect to their absorption spectra and polypeptide composition. The identity and probable function of eight bands were established by comparison of the wild-type pattern with those of isolated light-harvesting chlorophylla/b-protein complex and a number of nuclear gene mutants of barley. It was found that the mutantchlorina-f2, which lacks chlorophyllb, contains only three chlorophylla-proteins designated Chla-P1, Chla-P2 and Chl3-P3 according to a new system of nomenclature proposed in this paper. Chla-P1 contains the reaction centre of photosystem I (P700) and with the aid of the mutantviridis-m 29, Chla-P3 was deduced to be the most likely site of the reaction centre (P680) of photosystem II. Two chlorophylla/b-proteins were found, which differed in theira/b ratios and which are thought to play a role in light-harvesting or light-focusing. These were designated Chla/b-P1 and Chla/b-P2, the latter being found in multimeric complexes designated Chla/b-P2*, Chla/b-P2** and Chla/b-P2***, in order of increasing apparent molecular weight. In addition to these eight bands, there were two chlorophyll-containing bands in the wild-type pattern that were not Chla/b-P2 complexes and which were called Chl-P bands until further characterised.

Serine carboxypeptidases. A review

Abstract: Carboxypeptidases are proteolytic enzymes which only cleave the C-terminal peptide bond in polypeptides. Those characterized until now can, dependent on their catalytic mechanism, be classified as either metallo carboxypeptidases or as serine carboxypeptidases. Enzymes from the latter group are found in the vacuoles of higher plants and fungi and in the lysosomes of animal cells. Many fungi, in addition, excrete serine carboxypeptidases. Apparently, bacteria do not employ this group of enzymes.

Barley α-amylase/subtilisin inhibitor. I. Isolation and characterization

Abstract: A protein inhibitor of endogenous α-amylase 2 has been isolated from germinated barley by glycogen precipitation followed by cation-exchange chromatography. Preliminary kinetic analysis showed a mixed type mechanism of inhibition with an apparent Ki of 4×10−8M. The inhibitor formed well-defined complexes with barley malt α-amylase 2 and co-purified with the α-amylase by cycloheptaamylose affinity chromatography of glycogen precipitates. The inhibitor was inactive towards α-amylases from sorghum malt, hog pancreas, Aspergillus oryzae, and Bacillus subtilis. The amino acid composition and molecular weight near 21,000 were found to be the same as those of both “band-2 protein” previously identified in preparations of barley malt α-amylase and a specific subtilisin inhibitor from barley. Inhibition experiments confirmed that the malt α-amylase inhibitor is a strong inhibitor of subtilisin Carlsberg. Measurements of α-amylase activity in the presence of equimolar amounts of inhibitor and subtilisin showed that the inhibitor is “double headed”. The inhibitory activity towards α-amylase was lost after treatment of the inhibitor at 70 °C for 15 min. Isoelectric focusing patterns confirmed that the partially heat-labile, basic α-amylase isozymes (pI=6.6) of barley malt are complexes of α-amylase 2 (pI=6.2) and the inhibitor (pI=7.2). Evidence is presented to suggest that proteins with properties similar to those of the barley inhibitor are present in other cereals including wheat and rye. Possible in vivo functions and some practical aspects of the barley inhibitor are discussed.