Biomedical subjects

S O Andersen

Publications and source records attributed to S O Andersen.

At least 37 records · Page 2Linked to original sources

PubMed1994

Cuticle-catalyzed coupling between polyamino acids and N-acetyldopamine.

N-[2-14C]Acetyldopamine (NADA) was incubated in vitro with a series of homopolyamino acids or proteins in the presence of cell-free cuticle from locusts. The oxidized NADA was bound to the materials in varying degrees. The results indicate that lysine and histidine sidechains in the cuticular proteins might be the most likely candidates as participants in the crosslinking process in agreement with the results obtained by NMR.

Amino Acids↗

PubMed1994

The primary structure of an endocuticular protein from two locus species, Locusta migratoria and Schistocerca gregaria, determined by a combination of mass spectrometry and automatic Edman degradation.

The complete primary structures of two variants of a protein, Abd-5, isolated from the endocuticles of the migratory locust Locusta migratoria and the desert locust Schistocerca gregaria, have been determined. The proteins from the two species are N-terminally blocked with pyroglutamic acid. Their sequences differed only in two positions. Comparison of the sequences to those of other cuticular proteins shows that moderate homologies exist to 11 other cuticular proteins from insects representing four different orders. Amino acid residues in certain positions appear to be strictly conserved.

Amino Acid Sequence↗

PubMed1993

Combined plasma-desorption mass spectrometry and Edman degradation applied to simultaneous sequence determination of isoforms of structural proteins from the cuticle of Locusta migratoria.

The primary structures of two basic low-molecular-mass proteins, Lm-67 and Lm-70 from the pharate cuticle of the migratory locust, Locusta migratoria, were determined. The sequencing strategy was based on combined use of plasma--desorption mass spectrometry (PDMS) and automatic Edman degradation of the proteins and their enzymically derived peptides. The mass-spectral data showed the presence of two proteins in each preparation. For protein preparation Lm-67, this was indicated by the mass spectrum of the intact protein. For protein preparation Lm-70, the presence of two variants only became evident by mass-spectrometric analysis of the enzymically derived peptides. Both proteins show strong similarity to other exocuticular proteins from L. migratoria.

Amino Acid Sequence↗

PubMed1993

Primary structure of a 14 kDa basic structural protein (Lm-76) from the cuticle of the migratory locust, Locusta migratoria.

The complete amino acid sequence of a 14 kDa structural protein (LM-76) isolated from pharate cuticle of the locust, Locusta migratoria, was determined by Edman degradation of the intact protein and enzymatically derived peptides. Plasma desorption and electrospray mass spectrometry was used as an integrated part of the structure determination. Protein Lm-76 has characteristics similar to proteins previously isolated from the pharate locust. The amino acid composition shows a high content of alanine (32%) and absence of the amino acids Glu, Cys, Met, Phe and Trp. The sequence has a central hydrophilic region surrounded by two hydrophobic regions with 7 repeats of a (Tyr)-Ala-Ala-Pro-Ala/Val motif. The conservation around the prolyl residues within this sequence motif is demonstrated for the hitherto sequenced presumptive exocuticle proteins from L. migratoria. The N-terminal region of protein Lm-76 is enriched in the amino acids Gly, Leu and Tyr located in the conserved sequence NH2-Gly-Tyr-Leu-Gly-Gly-(Tyr)-.

Amino Acid Sequence↗

PubMed1992

Phenoloxidase catalyzed coupling of catechols. Identification of novel coupling products.

Phenoloxidases from insect cuticle as well as from other sources oxidize catechols resulting in the formation of various coupling products. The two dominating products from 4-methylcatechol and the main product from N-acetyldopamine were purified and identified by means of plasma desorption and electron impact mass spectrometry and by 1H- and 13C-NMR spectroscopy. The main product from both catechols has a quinoid trihydroxybiphenyl structure, indicating oxidative coupling between a catechol and the corresponding trihydroxy derivative. The second product from 4-methylcatechol is a biphenyltetrol derivative, indicating oxidative coupling between two catechols.

Animals↗

PubMed1991

Determination of the covalent structure of an N- and C-terminally blocked glycoprotein from endocuticle of Locusta migratoria. Combined use of plasma desorption mass spectrometry and Edman degradation to study post-translationally modified proteins.

The complete structure of protein isolated from endocuticle of sexually mature locusts, Locusta migratoria, has been determined by a combination of automatic Edman degradation and plasma desorption mass spectrometry. The protein is extensively post-translationally modified. The N-terminal is 5-oxoproline (pyroglutamic acid) and the C-terminal proline residue is amidated. Furthermore, the protein is glycosylated by a single N-acetyl-galactosamine residue at one, two or three threonines. The N-terminal sequence was obtained by analysing the N-acetylated N,O-permethylated derivative using plasma desorption mass spectrometry. The position and type of carbohydrate were determined by combining an HPLC-based carbohydrate analysis with the peak pattern of the phenylthiohydantoin derivative in automatic sequencing and with mass information on peptides. The protein has pronounced similarity to cuticular proteins from larvae of diptera and lepidoptera, but only slight resemblance to the previously sequenced locust exocuticular proteins. This indicates a similarity between soft larval cuticles and locust endocuticle, a similarity which may extend to their mechanical properties.

Acetylgalactosamine↗

PubMed1991

Cuticular proteins from the shrimp, Pandalus borealis.

1. The percentages of mineral salts, chitin, and urea-extractable and non-extractable proteins were determined in pieces of cuticle from selected body regions of the shrimp, Pandalus borealis. 2. Two-dimensional gel-electrophoresis of the urea-extractable proteins shows that a large number of different proteins are present. Identical protein patterns are obtained from the various cuticular regions. 3. A fractionation scheme is presented, which is suitable for obtaining the major proteins in quantities sufficient for further characterization. The amino acid compositions are reported for several of the proteins.

Amino Acids↗

PubMed1989

Plasma-desorption mass spectrometry as an aid in protein sequence determination. Application of the method on a cuticular protein from the migratory locust (Locusta migratoria).

The complete amino acid sequence of a structural protein, protein 8, isolated from the pharate cuticle of the locust Locusta migratoria was determined. Protein 8 contains 148 amino acid residues and has an Mr of 15,224. By the extensive use of information obtained by plasma-desorption mass spectrometry (p.d.m.s.) it was possible to reduce the need for conventional sequence determination and to improve the reliability of the results. On the basis of the determined Mr of the intact protein all the peptides that constitute the complete sequence could be isolated from a time-course enzymic digestion. The isolated peptides were sequenced by using a combination of Edman degradation and carboxypeptidase digestion monitored by p.d.m.s. The alignment of the peptides was established from the time-course digestion and further verified by a second enzymic digestion. The primary structure of the protein consists of two hydrophilic and two hydrophobic regions. The hydrophobic regions are enriched in alanine, valine and proline and dominated by a repetitive sequence Ala-Ala-Pro-(Ala/Val). The sequence strengthens the view that the cuticle proteins belong to a unique family of structural proteins.

Amino Acid Sequence↗

PubMed1986

Primary structure of a structural protein from the cuticle of the migratory locust, Locusta migratoria.

The complete amino acid sequence of a structural protein isolated from pharate cuticle of the locust Locusta migratoria was determined. The protein has an unusual amino acid composition: 42% of the residues are alanine and only 14 of the 20 common amino acid residues are present. The primary structure consists of regions enriched in particular amino acid residues. The N-terminal region and a region close to the C-terminus are enriched in glycine. The rest of the protein is dominated by alanine, except for two short regions enriched in hydrophilic residues. Almost all the proline residues are situated in the alanine-rich regions in a conserved sequence 'A-A-P-A/V'. An internal duplication has taken place covering most of the protein except for the glycine-rich regions. Owing to the unusual features of the protein a combination of automated Edman degradations and plasma-desorption m.s. was used to determine the complete sequence. The protein does not show sequence homology to other proteins, but proteins divided into regions enriched in the same kind of amino acid residues have been isolated from other insect structures.

Amino Acid Sequence↗

PubMed1986

Isolation, characterization, and N-terminal sequence studies of cuticular proteins from the migratory locust, Locusta migratoria.

The cuticle of the migratory locust, Locusta migratoria, contains more than a hundred different structural proteins, which can be extracted before but not after the cuticle is sclerotized. Fourteen of the proteins have been purified, covering a pI range of 6.4-10.6 and a molecular mass range of 15.2-36.8 kDa. The amino acid sequence from the N-terminal, ranging in length over 10-59 residues, have been obtained for eight of the proteins. A number of similarities, both in amino acid composition and in sequences, indicate that the proteins belong to a new protein family, characterized by an N-terminal part which is rich either in glycine, tyrosine and leucine or in hydrophilic amino acids, followed by a very alanine-rich portion. Similarities between this family of proteins and other structural proteins from insects are discussed.

Amino Acid Sequence↗

PubMed1981

Electron impact, chemical ionization and field desorption mass spectrometry of substituted dihydroxyphenyl-benzodioxins isolated from insect cuticle. Occurrence of thermal decomposition and oligomerization reactions in the mass spectrometer.

The electron impact, field desorption and chemical ionization mass spectra of seven dihydroxyphenyl-benzodioxins isolated from insect cuticle are discussed. Reproducible electron impact and chemical ionization spectra are obtained as a result of thermal decomposition and either electron impact or chemical ionization. In some of the chemical ionization spectra dimerization of the thermal degradation products is observed. Structure determination is possible based upon the electron impact and field desorption spectra.

Catechols↗

PubMed1978

Structural cuticular proteins in termite queens.

The abdominal cuticle from queens of two termite species, Cubitermes fungifaber and Macrotermes bellicosus, has been investigated with respect to changes occurring during development of physogastry. The following properties have been determined: 1. Relative content of protein and chitin and the percentage of easily extracted protein. 2. Number of proteins separated by electrophoresis and their molecular weights. 3. Amino acid compositions of the intertergal and pleural membranes and of the neosclerites in M. bellicosus. The intertergal and pleural membranes appear to be typical "soft" cuticles, and the neosclerites must also be considered "soft" cuticles, although they are rather rigid.

Animals↗

PubMed1976