Enzyme purification by genetically attached polycysteine and polyphenylalanine affinity tails

Two novel affinity tails, polycysteine and polyphenylalanine, have been genetically attached to galactokinase (EC 2.7.1.6) and beta-galactosidase (EC 3.2.1.23) in order to facilitate their purification. A chemically synthesized DNA linker encoding four cysteine residues was thus fused in frame with the galactokinase gene. The gene product, cysteine galactokinase, was significantly retarded on a column of thiopropyl-Sepharose. Using pulse elution, cysteine galactokinase was eluted at 10 mM DTT. Under the condition used, native galactokinase did not bind to thiopropyl-Sepharose. Homopolymer tailing was employed to prepare a phenylalanine-modified beta-galactosidase. One of the obtained genetic transformants coding for a beta-galactosidase carrying 11 phenylalanine residues at the N-terminus of the enzyme was isolated. With the aid of hydrophobic interaction chromatography the modified enzyme could be purified to homogeneity on fast protein liquid chromatography using a phenyl-Superose column.

The relationship between mandibular morphology and apical root curvature in man

Two samples of individuals, a low-angle group and a high-angle group, were selected on the basis of the inclination of the lower border of their mandible, defined by the mandibular plane angle (ML/SNL) in profile radiographs. Apical root curvature of mandibular first and second premolars and molars on panoramic radiographs was compared between the two groups and related to mandibular morphology. In the low-angle group most teeth had more distally curved roots than in the high-angle group. Significant differences were found for the first premolars on both sides (p less than 0.001, p less than 0.05), the right second premolars (p less than 0.05) and the distal root of left first molars (p less than 0.05). Correlations were calculated between root curvature and two variables reflecting mandibular morphology, the mandibular plane angle and the gonial angle. The strongest associations were found between the first premolar roots and the gonial angle (rs = -0.75, p less than 0.001 and rs = -0.56, p less than 0.01, for right and left sides respectively). The association between mandibular morphology and root curvature is probably indirect, caused by tooth migration during root formation.

The design of a simple competitive ELISA using human proinsulin-alkaline phosphatase conjugates prepared by gene fusion

The gene encoding human proinsulin has been fused in-frame with the E. coli alkaline phosphatase gene (pho A) (EC 3.1.3.1). Two constructions are described. One construction consists of the entire proinsulin gene fused to the 5'-terminal end of pho A. In the other construction a 42 base pair DNA fragment has been deleted from the 3'-terminal end of the proinsulin gene. The two purified fusion proteins are enzymatically active showing a specific activity of 10-15 U/mg and 18-25 U/mg, respectively. The first construction exhibited insulin antigenicity and was used to design a simple competitive ELISA for insulin. The lower detection limit was found to be at least 2.5 ng/ml. Both fusion proteins were also shown to have potential for use in a competitive ELISA for proinsulin.

Solid and papillary epithelial neoplasm of the pancreas presenting as a traumatic cyst. Case report

A 16-year-old girl presented with a left-sided abdominal mass following blunt trauma. Clinically and ultrasonographically a pseudocyst of the pancreas was suspected. Computed tomography demonstrated a moderately vascularized tumour mass in the pancreatic tail, with a central cystic space. Distal pancreatectomy was subsequently performed. Histologic examination revealed a solid and papillary epithelial neoplasm of the pancreas. This is a well-defined clinicopathologic entity, mostly found in young women. Histologic evidence of aggressive behaviour is sometimes seen, and was found in the present case. The prognosis after surgical removal is good, however, which emphasizes the importance of recognizing this rare tumour.

Enzymatic wound cleaning and absorbable sutures. An experimental study on Varidase and Dexon sutures

The effect of an enzymatic preparation for wound cleaning (Varidase) on the mechanical properties of absorbable sutures (Dexon) was studied in vitro and in vivo in a rat model. In vitro the sutures demonstrated a significant decrease in strength (breaking strength and energy absorption) and extensibility after 12 days of incubation in saline. Incubation in Varidase, however, further decreased the mechanical properties significantly. The stiffness of the sutures was independent of treatment and time. In vivo changes of mechanical properties of the sutures resemble those of the in vitro study, except for a decrease in stiffness of the sutures. The sutures in a primary closed wound had the same strength (energy absorption) as the sutures of an open wound treated by saline, while the sutures of an open wound treated by Varidase tended to have a decreased strength (p = 0.08). This study supports the hypothesis that an enzymatic process may be involved in the degradation of Dexon. The continuous use of Varidase in Dexon-sutured wounds for a period longer than a few days is, therefore, questioned.

The primary structure of Escherichia coli glutaredoxin. Distant homology with thioredoxins in a superfamily of small proteins with a redox-active cystine disulfide/cysteine dithiol

An immunosorbent method using antiglutaredoxin-Sepharose was developed for purification of glutaredoxin in high yield from a mutant strain of Escherichia coli K 12 lacking thioredoxin reductase (C 10-17). The primary structure of the protein was determined by analyses of [14C]carboxymethylated glutaredoxin and its proteolytic fragments obtained by digestions with trypsin, clostripain, chymotrypsin and staphylococcal Glu-specific extracellular protease. The single active-center disulfide has the structure-Cys-Pro-Tyr-Cys-, with the half-cystine residues located at positions 11 and 14 in the polypeptide chain. In total the protein was deduced to have 85 residues corresponding to a molecular weight of 9674 for the reduced form of glutaredoxin, making it one of the smallest known enzymes (a glutathione-disulfide transhydrogenase). The half-cystines are identically spaced and similarly positioned in the N-terminal part of the protein when compared with a corresponding functionally active disulfide/dithiol in thioredoxins. Glutaredoxin is also distantly homologous with thioredoxins from phage T4 and E. coli, but extensive differences, even around the redox-active disulfide, distinguish glutaredoxin from the thioredoxins. Allowing for deletions in the glutaredoxin sequence (or insertions in the T4 thioredoxin sequence) at four places, there are identical residues at 25 positions of the 77 compared (= 32% identity). The results establish that glutaredoxin belongs to the same superfamily of small redox proteins as the thioredoxins. The structures are, however, subject to large changes, only four positions have residues identical among all presently analyzed forms. The fluorescence of reduced and oxidized glutaredoxin demonstrates an increase in the quantum yield of the tyrosine emission upon reduction with dithiothreitol. Differences in the spectra support the presence of tyrosine adjacent to the redox-active disulfide bridge. They also confirm that glutaredoxin lacks the disulfide-adjacent tryptophan residues of E. coli thioredoxin. There are known to be great differences between the bacterial E. coli and phage T4 forms of thioredoxin. The glutaredoxin structure is most similar to the phage type, both with respect to size of the polypeptide chain and to actual sequence. From the structural results and the previously known functional similarities it appears possible that the phage thioredoxin may have evolved from an early glutaredoxin gene. The mixed properties are compatible with this conclusion, the superfamily assignment, and the differences in biological activity.

Characterization of the humoral immune response in Plasmodium falciparum malaria. II. IgG subclass levels of anti-P. falciparum antibodies in different sera

The IgG subclass levels of anti-Plasmodium falciparum antibodies in human sera were determined in ELISA with monoclonal mouse antibodies specific for the human IgG subclasses as analytical reagents. The parasite antigen was a trophozoite/schizont enriched preparation of in vitro cultivated P. falciparum. Serum samples were from Swedish malaria patients and adult Liberians. Parasite specific antibodies were found in all four subclasses. Relatively elevated levels of IgG1 antibodies were found both in Swedish patients and in the Liberians. Relative to the Liberians, high IgG2 antibody levels were seen in most Swedish patients. In Liberian sera but not in those from Swedish patients elevated IgG3 levels were found. In two Swedish patients followed consecutively for a period of 15 weeks, elevated levels of IgG1 and IgG3 antibodies were seen after relapse. No differences between the groups in regard to the levels of IgG4 antibodies were noticed. The differences between the Swedish patients and the Liberians were also in part reflected by differences in the total amounts of the four IgG subclasses.

The role of movements in the development of sutural and diarthrodial joints tested by long-term paralysis of chick embryos

Chick embryos were paralysed in ovo with a neuromuscular blocking agent between 8 and 20 days of incubation. To evaluate the rôle of muscular activity in the development of sutural articulations, sutures of the cranial vault of control and paralysed embryos were studied histologically and the findings compared with the effect of the agent on the development of the ankle joint and some synovial joints of the jaws. Paralysed embryos showed a consistent lack of development of joint cavities in synovial joints. In most embryos, fusion of opposing cartilaginous elements had occurred. In contrast to synovial joints, sutural articulation showed a micromorphology comparable to that of controls. The findings indicate that different embryonic factors regulate the development of sutural and synovial articulations. Movements of neuromuscular origin play no essential role in the morphogenetic development of sutures, but are a prerequisite for the formation of joint cavities and other specialised structures of synovial joints.

The primary structure of subunit II of NADH dehydrogenase from bovine-heart mitochondria

Subunit II (with a molecular mass of about 24000 dalton, approximately 24 kDA) of NADH dehydrogenase from beef heart mitochondria was [ 14C ]carboxymethylated and cleaved with CNBr and proteolytic enzymes. Sequence analyses of purified fragments suggest that the subunit is composed of a homogeneous polypeptide chain, containing just over 230 residues. The primary structure of this chain was established except for a 14-residue internal part which was only determined by composition. The amino acid sequence suggests that four cysteine residues are involved in the binding of an iron-sulfur cluster. The subunit contains no long hydrophobic segment, in contrast to structures often found in membrane proteins, but in agreement with a model where the functional unit of NADH dehydrogenase in the membrane is shielded by other intra-membrane proteins. The polypeptide has a weak similarity to the iron-sulfur binding region of ferredoxin and has interesting but possibly insignificant similarities to parts of previously compared flavin-linked enzymes.