Stability of cervical esophagogastrostomy via hand-sewn anastomosis after esophagectomy for esophageal cancer

The aim of the present study is to evaluate the outcome of hand-sewn esophagogastric anastomosis during radical esophagectomy for esophageal cancer. The outcomes of 467 consecutive esophageal cancer patients who underwent cervical esophagogastric anastomosis using interrupted and double-layered sutures after radical esophagectomy via right thoracotomy or thoracoscopic surgery were retrospectively reviewed. Anastomotic leakage, including conduit necrosis, occurred in 11 of 467 patients (2.4%); 7 of 11 (63.6%) cases experienced only minor leakage, whereas the other four (36.4%) patients had major leakage that required surgical or radiologic intervention, including two patients of conduit necrosis. Anastomotic leakages were more frequently observed after retrosternal reconstruction compared with the posterior mediastinal route (P < 0.0001). The median time to healing of leakage was 40 days (range: 14-97 days). Two patients (2/467, 0.4%) died in the hospital due to sepsis caused by the leakage and conduit necrosis. Twelve patients (2.6%) developed anastomotic stenosis, which was improved by dilatation in all patients. Hand-sewn cervical esophagogastric anastomosis is a stable and highly safe method of radical esophagectomy for esophageal cancer.

Reappraisal of the clinical significance of CD7 expression in association with cytogenetics in de novo acute myeloid leukaemia

Debate exists over whether CD7 expression indicates an unfavourable prognosis in de novo acute myeloid leukaemia (AML). Meanwhile, the type of cytogenetics is a strong prognostic factor in AML. We analysed 256 de novo adult AML cases and found that the proportion of CD7+ cases increased stepwise from the cases with favourable cytogenetics to the cases with intermediate and unfavourable cytogenetics (3 out of 69 cases, 51 out of 140 cases and 25 out of 47 cases respectively, P < 0.0001). CD7-positivity adversely affected the survival only in the cases with unfavourable cytogenetics (P < 0.03). We recommend that CD7 expression in AML be interpreted in association with the cytogenetics.

Association between natural killer cell activity and infection in immunologically normal elderly people

Congenital patients who lack natural killer (NK) cell activity experience repeated polymicrobial infections. NK cell activity varies significantly among normal people, but it is unknown whether this variation influences their ability to fight infections. This study examined this concern. NK cell activity and other variables, i.e. age, sex, performance status (PS), serum albumin value, lymphocyte and neutrophil counts, various lymphocyte subsets, etc. were determined for 108 immunologically normal elderly subjects who were in nursing homes due to an impaired PS. We analysed for correlations between these variables and the follow-up results of the subjects. Forty-eight subjects developed infection(s) during the first year of follow-up. A low NK cell activity was associated with the development of infection (P = 0.0105, multivariate logistic regression analysis). The relative risk for the development of infection increased in accordance with the decrease in the NK cell activity. Eleven subjects died of infection during the study period. A low NK cell activity was associated with short survival due to infection (P = 0.0056, multivariate Cox's proportional-hazards regression analysis). Our data indicate that low NK cell activity is associated with development of infections and death due to infection in immunologically normal elderly subjects with an impaired PS.

Chlorophyll degradation in a Chlamydomonas reinhardtii mutant: an accumulation of pyropheophorbide a by anaerobiosis

Chlorophyll degradation was investigated in cells of a chlorophyll b-less mutant of Chlamydomonas reinhardtii under aerobic and anaerobic conditions. During degradation of chlorophyll under anaerobic conditions, chlorophyll catabolite P535, an open-tetrapyrrole, was not excreted, but pyropheophorbide a was accumulated as the end product with a transient accumulation of chlorophyllide a and pheophorbide a in cells, in contrast to the breakdown under aerobic conditions. It is likely that in the absence of oxygen, degradation of chlorophyll a proceeds to pyropheophorbide a by three consecutive reactions, dephytylation, metal-releasing and demethoxycarbonylation, and then stops due to a limitation of the oxygen that the monooxygenase reaction requires for bilin formation. A novel enzyme catalyzing demethoxycarbonylation of pheophorbide a was partially purified. The enzyme activity increased dependent on the age of cells, and its increase was completely suppressed by cycloheximide. Production of P535 was also dependent on cytoplasmic protein synthesis.

Purification of a novel type of SDS-dependent protease in maize using a monoclonal antibody

A protease which was activated by SDS was purified to homogeneity from maize leaves. On the basis of its proteolytic activity towards ribulose-1,5-bisphosphate carboxylase/ oxygenase (Rubisco) or a synthesized peptide, the purification was carried out using immunoaffinity chromatography with a monoclonal antibody raised against a partially purified enzyme by native gradient PAGE. The purified protease showed three bands at 40, 15, and 13 kDa on SDS-PAGE, indicating that it was composed of heterogeneous subunits. The protease was specifically activated by SDS (optimum = 0.4% for Rubisco proteolysis), but not by poly-L-lysine, fatty acids, or ATP. The protease had a pH optimum around 4.9. beta-Mercaptoethanol stimulated the activity only in the presence of SDS. The proteolytic activity was sensitive to E-64 and leupeptin but was resistant to EDTA, suggesting that the enzyme was an SH-protease. Thus, this enzyme is a novel type of SDS-dependent protease which differs from proteasome, matrix metalloproteinase, and other proteases reported in many organisms.

Nucleotide sequence and transcriptional analysis of the flanking region of the gene (spb) for the trans-acting factor that controls light-mediated expression of the puf operon in Rhodobacter sphaeroides

We recently reported the existence of a trans-acting factor (SPB) in Rhodobacter sphaeroides that repressed the expression of the puf operon during illumination. SPB was somewhat homologous to HvrA of Rhodobacter capsulatus, but these proteins appear to have functionally different properties. We now report an analysis of the flanking region of spb in the genome of R.sphaeroides, and we show that spb is a positional counterpart of hvrA of R. capsulatus. The region directly downstream of spb was found to contain three genes, two of which were highly homologous to orf5 and ahcY in R. capsulatus. However, a gene corresponding to hvrB, which controls the expression of orf5 and ahcY in R. capsulatus, was absent in R. sphaeroides. The level of the transcript of ahcY did not change in cells grown under photosynthetic and by respiratory conditions. By contrast, orf5 was transcribed at a higher rate in photosynthetically grown cells under high-intensity light than under low-intensity light, indicating features of transcription different from those in R. capsulatus. A third gene, orf318, which was absent in the corresponding region of R. capsulatus, encoded an amino acid sequence that was significantly homologous to the consensus sequence of RfaI and RfaJ of E.coli, which are glycosyl transferases involved in the synthesis of lipopolysaccharide. orf318 was transcribed in the opposite direction to ahcY, and at only a low level, under all conditions tested.

Cloning of the gene for monogalactosyldiacylglycerol synthase and its evolutionary origin

Monogalactosyldiacylglycerol (MGDG) synthase (UDPgalactose:1,2-diacylglycerol 3-beta-D-galactosyltransferase; EC 2.4.1.46) catalyzes formation of MGDG, a major structural lipid of chloroplast. We cloned a cDNA for the synthase from cucumber cDNA library. The full-length cDNA clone was 2142 bp, and it contains a 1575-bp open reading frame encoding 525 aa. The open reading frame consists of the regions for a mature protein (422 aa; Mr of 46,552) and transit peptide to chloroplast (103 aa). Although the molecular weight of mature protein region matched that purified from cucumber cotyledons, it was quite different from those purified from spinach (approximately 20 kDa) reported by other groups. The mature region of the protein was expressed in Escherichia coli as a fusion protein with glutathione S-transferase. The expression in E. coli showed that the protein catalyzed MGDG synthesis very efficiently. Therefore, we concluded that the cDNA encodes MGDG synthase in cucumber. In addition, the deduced amino acid sequence of the MGDG synthase cDNA showed homology with MurG of Bacillus subtilis and E. coli, which encode a glycosyltransferase catalyzing the last step of peptidoglycan synthesis in bacteria. This sequence homology implies that the machinery of chloroplast membrane biosynthesis is evolutionarily derived from that of cell wall biosynthesis in bacteria. This is consistent with the endosymbiotic hypothesis of chloroplast formation.

A transcription factor with a leucine-zipper motif involved in light-dependent inhibition of expression of the puf operon in the photosynthetic bacterium Rhodobacter sphaeroides

In the purple nonsulfur photosynthetic bacterium Rhodobacter sphaeroides the synthesis of components of the photosystem is regulated in response to oxygen tension and light intensity. We have purified and cloned a trans-acting protein (SPB) that binds to the promoter region of the puf operon, which encodes the apoproteins of light-harvesting complex I and the reaction center. The SPB was composed of a single polypeptide with an apparent molecular mass of 15.0 kDa. The nucleotide sequence of the spb gene was determined. The gene encoded 104 amino acid residues, which correspond to a molecular mass of 11.5 kDa. SPB exhibited 53% homology to HvrA in Rhodobacter capsulatus. The deduced amino acid sequence indicated that SPB contained a region with homology to the leucine-zipper motif of c-JUN, a transcription factor in eukaryotes, and SPB also had a DNA-binding domain on the amino-terminal side of the leucine-zipper motif. The leucine-zipper motif of SPB might contribute to the formation of a dimer. Northern analysis indicated that spb was constitutively and monocistronically transcribed in R. sphaeroides, irrespective of growth conditions. Structural and functional differences between SPB and HvrA are discussed.

Induction of a novel cytochrome P450 (CYP93 family) by methyl jasmonate in soybean suspension-cultured cells

We isolated a cDNA encoding a novel cytochrome P450 (CYP93A1) from soybean suspension-cultured cells that had been treated with methyl jasmonate (MeJA). The amino acid sequence of the gene product had 30-40% identity with those of other plant P450s. The protein contained the heme-binding domain which is highly conserved among plant P450s. Transcription of the cytochrome P450 gene in soybean cells was induced by 30 microM MeJA even in the presence of cycloheximide, and reached maximum level 6 h after MeJA treatment. This is the first report of a plant cytochrome P450 gene whose transcription is induced by MeJA even without protein synthesis.

Expression of the puf operon in an aerobic photosynthetic bacterium, Roseobacter denitrificans

The effects of oxygen and light on the expression of the puf operon were investigated in Roseobacter denitrificans in a comparison with those in Rhodobacter sphaeroides. In darkness, the levels of the total puf mRNA in Ros. denitrificans were about 1.3 times those in Rb. sphaeroides at low concentrations of oxygen, reflecting the accumulation of bacteriochlorophyll and carotenoids. The oxygen tension, up to 94% saturation of dissolved oxygen, did not affect the levels of the total puf transcripts in Ros. denitrificans, whereas those in Rb. sphaeroides were reduced to 55% of the maximum level even at 50% saturation. Four puf-specific transcripts were detected: a 0.5-kb transcript was the most abundant; 1.2-kb and 1.9-kb transcripts accumulated at low levels; and a 3.5-kb transcript accumulated at very low levels under all conditions tested. The levels of the individual transcripts were barely affected by molecular oxygen. An S-1 nuclease protection assay revealed that the 0.5-kb transcript encoded the LHI-alpha and LHI-beta subunits (pufBA), the 1.2-kb transcript encoded puf-BA and part of pufL, and the 1.9-kb transcript encoded pufBAL and part of pufM. It was not clear whether the 3.5-kb transcript encoded the entire pufBALM and the gene for the polypeptide moiety of cytochrome c. The difference in levels between the 0.5-kb transcript and the other transcripts (1.2 kb, 1.9 kb, and 3.5 kb) was presumed to be due to the presence of several stem-loop structures at the 3' terminus of the 0.5-kb transcript which acted as terminators of transcription and, possibly, as protection against nucleolytic digestion. Light inhibited the expression of the puf operon in Ros. denitrificans more effectively than that in Rb. sphaeroides. The insensitivity to oxygen, as well as the sensitivity to light, of the expression of the puf operon in Ros. denitrificans, which was different from that in Rb. sphaeroides, seemed to represent a mode of adaptation that allowed the former cells to avoid photodynamic damage by light under highly aerobic conditions.

Separation of mono- and divinyl chlorophyll species by high-performance liquid chromatography using an octadecyl polyvinyl alcohol polymer column

Most of the chlorophylls and their related compounds from nonesterified chlorophyllide to esterified pheophytin were separated by high- performance liquid chromatography using a wide pore, C(18) polyvinyl alcohol polymer column with an elution using a binary gradient starting from a buffered mobile phase. The high selectivity of this system enabled not only the separation of common chlorophyll species but also the resolution of structurally similar compounds such as mono- and divinyl chlorophyllide and pheophorbide species which usually coelute on monomeric bonded phases. The method is successfully applied to analyses of the pigments extracted from green and etiolated tissues of higher plants and photosynthetic bacterial cells.

Cloning, subcellular localization and expression of CHL1, a subunit of magnesium-chelatase in soybean

Mg-insertion is the first committed step in chlorophyll synthesis and is catalyzed by Mg-chelatase. In photosynthetic bacteria, bchI gene product was suggested to be a subunit of Mg-chelatase. We isolated a bchI homolog from a soybean cDNA library and designated it as chlI. CHLI consisted of 421 amino acid residues and the sequence exhibited a high similarity to other BchI homologs. CHLI contained an ATP-binding motif found in other BchI homologs. CHLI was localized in the soluble fraction in soybean chloroplasts, suggesting that it was a stromal subunit of Mg-chelatase. chlI mRNA in cell culture (SB-P) of soybean was reversibly induced by light.

Light-enhanced gene expression of NADPH-protochlorophyllide oxidoreductase in cucumber

The NADPH-protochlorophyllide oxidoreductase (NPR) is a well known enzyme catalyzing photoconversion of protochlorophyllide to chlorophyllide a and its expression is negatively regulated by light. We cloned a NPR cDNA from cucumber (Cucumis sativus L.). The cDNA contained an open reading frame encoding 398 amino acids and amino acid sequence showed high similarity to those of NPR from other plants. Contrasting with most other plants, the levels of the NPR mRNA increased in etiolated cotyledons of cucumber when they were illuminated with continuous light, suggesting that the expression of this NPR gene was strongly related to chlorophyll synthesis in green leaves.

A putative transcription factor binding to the upstream region of the puf operon in Rhodobacter sphaeroides

Gel shift assays of the upstream region of the puf operon in Rhodobacter sphaeroides were performed using cell-free extracts from cells grown under various culture conditions. The results suggested that a protein binding to the upstream region functioned as a repressor-like substance of the expression of the operon by oxygen tension or light. The density of the shifted band of cell-free extracts from cells irradiated with blue light under semi-aerobic conditions was higher than that with red light. Phosphatase treatment of the cell-free extracts strongly increased the DNA-binding affinity of the protein.

Some properties and occurrence of cytochrome c-552 in the aerobic photosynthetic bacterium Roseobacter denitrificans

Characteristics and occurrence of cytochrome c-552 from an aerobic photosynthetic bacterium, Roseobacter denitrificans, were described. Relative molecular mass of the cytrochrome was 13.5 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and 15,000 by gel filtration. This cytochrome was a acidic protein having a pI of 5.6 and Em was +215 mV at pH 7.0. Absorption peaks were at 278, 408 and 524 nm in the oxidized form and 416, 523 and 552 nm in the reduced form. Amino acid composition and N-terminal amino acid sequence of cytochrome c-552 determined for 24 residues had low similarities to those of cytochrome c-551 of this bacterium, which is homologous to cytochrome c2, although the physico-chemical properties of these two cytochromes were similar to each other. Cytochrome c-552 was maximally synthesized in the light under aerobic conditions but not in the dark. The synthesis also occurred in the presence of alternative acceptors such as trimethylamine N-oxide (TMAO) and nitrate under anaerobic conditions. Our results suggest that cytochrome c-552 is involved in TMAO respiration and denitrification in R. denitrificans, although the effect of light remains to be solved.

Monovinyl and divinyl protochlorophyllide pools in etiolated tissues of higher plants

The composition of chlorophyll-precursor pigments, particularly the contents of monovinyl (MV) and divinyl (DV) protochlorophyllides (Pchlides), in etiolated tissues of higher plants were determined by polyethylene-column HPLC (Y. Shioi, S. I. Beale [1987] Anal Biochem 162: 493-499), which enables the complete separation of these pigments. DV-Pchlide was ubiquitous in etiolated tissue of higher plants. From the analyses of 24 plant species belonging to 17 different families, it was shown that the concentration of DV-Pchlide was strongly dependent on the plant species and the age of the plants. The ratio of DV-Pchlide to MV-Pchlide in high DV-Pchlide plants such as cucumber and leaf mustard decreased sharply with increasing age. Levels of DV-Pchlide in Gramineae plants were considerably lower at all ages compared with those of other plants. Etiolated tissues of higher plants such as barley and corn were, therefore, good sources of MV-Pchlide. Absorption spectra of the purified MV- and DV-Pchlides in ether are presented and compared.

Distribution and Physiology of Aerobic Bacteria Containing Bacteriochlorophyll a on the East and West Coasts of Australia

Aerobic heterotrophic bacteria containing bacteriochlorophyll were isolated from specimens from a wide variety of marine environments on the west (Shark Bay, Lake Clifton, Lake Heyward, and Perth) and east (near Townsville and Brisbane) coasts of Australia. The bacteria were found in a high proportion (10 to 30%) of the total heterotrophic bacterial strains isolated from marine algae, seagrasses, stromatolites, the epiphytes on stromatolites, seawater, and sands; in some cases they constituted up to 49% of the total. This is much higher than the previous report of 6% from Japan. A high percentage, 13%, was also found in the seawater of Hamelin Pool, at Shark Bay, where the salinity was 66%. The number of these bacteria was generally low in seawater and sands, with a few exceptions. There were no aerobic bacteriochlorophyll-containing bacteria on sponges or corals. The isolated strains were orange or pink, and most had absorption maxima around 800 and 850 to 870 nm, the latter range being the absorption of bacteriochlorophyll a in vivo. The maximum bacteriochlorophyll content was 1 nmol/mg (dry weight) of bacterial cells. Most of the bacteria did not grow phototrophically under anaerobic conditions in a broth medium containing succinate. Cells and cell extracts grown under aerobic conditions had photochemical activities such as reversible photooxidations of the reaction center and cytochrome(s). Some strains showed denitrifying activity. The optimal salinity for bacterial growth varied between strains.

Two types of cytochrome cd1 in the aerobic photosynthetic bacterium, Erythrobacter sp. OCh 114

Components I and II of cytochrome cd1 which had different spectral features were purified from the aerobic photosynthetic bacterium, Erythrobacter sp. strain OCh 114. Component I showed an absorption maxima at 700 and 406 nm in the oxidized form, and at 621, 552.5, 548 and 416 nm in the reduced form. Component II showed an absorption maxima at 635 and 410 nm in the oxidized form and at 628, 552.5, 548 and 417 nm in the reduced form. The relative molecular mass, Mr, of both cytochromes was determined to be 135,000 with two identical subunits. Components I and II showed pI values of 7.6 and 6.8, respectively. The redox potential of hemes ranged from +234 mV to +242 mV, except for the heme d1 of component I (Em7 = +134 mV). Components I and II showed both cytochrome c oxidase and nitrite reductase activities. Cytochrome c oxidase activity was strongly inhibited by a low concentration of nitrite and cyanide. Erythrobacter cytochromes c-551 and c-552 were utilized as electron donors for the cytochrome c oxidase reaction. The high affinity of cytochrome c-552 to component II (Km = 1.27 microM) suggested a physiological significance for this cytochrome. Erythrobacter cytochromes cd1 are unique in their presence in cells grown under aerobic conditions as compared to other bacterial cytochromes cd1 which are formed only under denitrifying conditions.

Selective inhibition of chlorophyll biosynthesis by nicotinamide

Rhodobacter sphaeroides grown in the presence of nicotinamide excreted bacteriochlorophyll precursors, 2,4-divinyl protochlorophyllide (DV-Pchlide) and a small amount of 2-monovinyl protochlorophyllide (MV-Pchlide). Accumulation of these pigments indicates that nicotinamide inhibited the bacteriochlorophyll biosynthetic pathway site-specifically between DV-Pchlide and MV-Pchlide. This phenomenon is also observed in an aerobic photosynthetic bacterium, Erythrobacter sp. OCh 114. Among 12 nicotinamide derivatives and isomers tested, only nicotinamide was effective, indicating that in addition to the completeness of the pyridine ring skeleton at positions 1 to 3, the carboxylic acid amide group is essential for this inhibition. The technique described in this report permits the simple preparation of large quantities of DV-Pchlide.

Control of bacteriochlorophyll accumulation by light in an aerobic photosynthetic bacterium, Erythrobacter sp. OCh 114

The effect of light on bacteriochlorophyll (Bchl) accumulation as well as the activity of two enzymes in the initial step of the tetrapyrrole biosynthetic pathway was examined in an aerobic photosynthetic bacterium, Erythrobacter sp. strain OCh 114. Light clearly regulated the Bchl and carotenoid accumulation, completely suppressing their levels at high light intensity. However, porphyrin and Bchl precursors were not found in either the cells or the growth medium of lighted culture. The level of Bchl showed an inverse relationship to the light energy flux. Kinetic studies showed a Hill coefficient of n = 3.3 (r = 0.973), indicating a positive cooperativity. Bchl accumulation was stopped immediately upon illumination without any lag or overshoot. Despite low Bchl content, the activities of 5-aminolevulinic acid synthetase and porphobilinogen synthase were rather stimulated, but not suppressed by light. The high activity of enzymes coincided with the results that heme contents, particularly cytochrome c and catalase activity, were increased in light-grown cells. These results suggest that light regulated Bchl accumulation, but not Bchl biosynthesis and that the effect of light is to render newly formed pigment molecules unstable.

Inhibition of porphyrin biosynthesis by exogenous 5-aminolevulinic acid in an aerobic photosynthetic bacterium, Erythrobacter sp. OCh 114

Exogenously administered 5-aminolevulinic acid (ALA) inhibited the formation of bacteriochlorophyll a (Bchl a) in a dose-dependent manner in the aerobic photosynthetic bacterium, Erythrobacter sp. strain OCh 114, under dark growth conditions. The ALA concentration required for half-inhibition after 24-h growth was estimated to be about 3.0 mM. Porphyrin and Bchl precursors were not found in either the cells or the growth medium. The same inhibition was also observed with cytochrome c formation. When ALA was incubated with intact cells, a large amount of ALA was converted to an unknown metabolite. The pH optimum of the conversion was 7.8. The metabolite did not react with Ehrlich's reagent, but did so with ninhydrin, giving a yellow color. Based on analyses by several techniques including mass spectrometry, ir spectrometry, and paper electrophoresis, it was identified as 4-hydroxy-5-aminovaleric acid (HAVA). Authentic HAVA prepared from ALA was a competitive inhibitor of the enzyme, porphobilinogen synthase of Erythrobacter. The Ki value for authentic HAVA was calculated to be 2.4 mM from a Dixon plot and the HAVA concentration required for half-inhibition was 17 mM. It is concluded that in Erythrobacter cells, exogenous ALA is converted to the metabolite, HAVA, which is responsible for the inhibition of porphobilinogen synthase as well as that of Bchl a and cytochrome formation.

Purification and Characterization of Two Benzoyl-l-Tyrosine p-Nitroanilide Hydrolases from Etiolated Leaves of Zea mays L

Two benzoyl-l-tyrosine p-nitroanilide hydrolases (BTPAases I and II) were purified from the etiolated leaves of Zea mays L. and characterized. BTPAase I was electrophoretically homogeneous and consisted of two identical subunits having a molecular weight of 53,000. The molecular weight of BTPAase II was 65,000. The Michaelis constants for substrate, BTPA, were 4 millimolar and 1.3 millimolar for BTPAases I and II, respectively. Based on the action of various inhibitors on both enzyme activities, these enzymes were classified as serine proteases. BTPAase I showed caseinolytic activity at neutral pH and the activity was strongly inhibited by the serine protease inhibitors.

Polyethylene-based high-performance liquid chromatography of chloroplast pigments: resolution of mono- and divinyl chlorophyllides and other pigment mixtures

In addition to most chlorophylls and their derivatives, monovinyl and divinyl chlorophyll species were separated by high-performance liquid chromatography, using a polyethylene column and a simple elution with aqueous acetone. Peak retention and resolution of the pigment separation were greatly increased by increasing the polarity of the mobile phase and also by decreasing the column temperature. Polyethylene chromatography showed chlorophyll separation behavior similar to that of the octadecyl silica column, but it showed no adsorption of the pigment species containing free carboxylic acid groups, enabling the complete separation of chlorophylls and their derivatives. Polyethylene is a superior alternative stationary phase to the known reversed-phase materials for chlorophyll separation and analysis.

Purification and characterization of benzoyl-L-arginine p-nitroanilide hydrolase from etiolated leaves of Zea mays

Benzoyl-L-arginine p-nitroanilide hydrolase in the etiolated leaves of Zea mays L. has been purified 1,266-fold by a combination of gel filtration, ion exchange, and hydrophobic chromatography with a recovery of 13%. The specific activity of the purified enzyme is 5.7 units/mg protein. The enzyme is an acidic protein with a pI value of 4.6 and optimum pH of 8.2. The molecular weight of the enzyme was estimated to be 59,000. Substrate inhibition was observed at a concentration higher than 30 microM BAPA and the apparent Km for BAPA was 29 microM at pH 8.0. The enzyme activity was inhibited by sulfhydryl reagents, leupeptin, antipain, and N-tosyl-L-lysine chloromethyl ketone. The inhibitor study suggests that the enzyme belongs to the class of the sulfhydryl proteases.

Purification and properties of L-alanine:4,5-dioxovalerate aminotransferase from Chlorella regularis

The enzyme L-alanine:4,5-dioxovalerate aminotransferase (EC 2.6.1.43), which catalyzes the synthesis of 5-aminolevulinic acid, was purified 161-fold from Chlorella regularis. The enzyme also showed L-alanine:glyoxylate aminotransferase activity (EC 2.6.1.44). The activity of glyoxylate aminotransferase was 56-fold greater than that of 4,5-dioxovalerate aminotransferase. The ratio of the two activities remained nearly constant during purification, and when the enzyme was subjected to a variety of treatments. 4,5-Dioxovalerate aminotransferase activity was competitively inhibited by glyoxylate, with a Ki value of 0.5 mM. Double-reciprocal plots of velocity versus 4,5-dioxovalerate with varying L-alanine concentrations indicate a ping-pong reaction mechanism. The apparent Km values for 4,5-dioxovalerate and L-alanine were 0.12 and 3.5 mM, respectively. The enzyme is an acidic protein having an isoelectric point of 4.8. The molecular weight of the enzyme was estimated to be 126,000, with two identical subunits. These results suggest that, in Chlorella, as in bovine liver mitochondria and Euglena, both 4,5-dioxovalerate and glyoxylate aminotransferase activities are associated with the same protein. From the activity ratio of transamination and catalytic properties, it is concluded that this enzyme does not function primarily as a part of the 5-carbon pathway to 5-aminolevulinic acid synthesis.

Terminal steps of bacteriochlorophyll a phytol formation in purple photosynthetic bacteria

Four chemically different bacteriochlorophylls (Bchls) a esterified with geranylgeraniol, dihydrogeranylgeraniol, tetrahydrogeranylgeraniol, and phytol have been detected by high-pressure liquid chromatography in cell extracts from Rhodopseudomonas sphaeroides and Chromatium vinosum. Bchl a containing phytol is the principal component, and the other three Bchls a comprise about 4% of the total Bchls a in stationary-phase cells of R. sphaeroides and C. vinosum. The high levels of the minor pigments occur in the beginning of Bchl a phytol formation, indicating that they are not degradation products, but intermediates of Bchl a phytol formation.

Analysis of porphyrin precursors, 5-aminolevulinic acid derivatives by isotachophoresis

Porphyrin precursors, 5-aminolevulinic acid (ALA), 4,5-dioxovaleric acid (DOVA), and porphobilinogen (PBG) can be simultaneously and conveniently analyzed by isotachophoresis. The quantitative analysis requires a minimum of 12 nmol for ALA, 4 nmol for DOVA, and 35 nmol for PBG. The reproducibility determined as coefficient of variation for qualitative and quantitative determination is within 4 and 5%, respectively. Isotachophoresis permits simple, efficient and quantitative detection, and identification of ALA derivatives in a mixture.

Compositional heterogeneity of protochlorophyllide ester in etiolated leaves of higher plants

The formation and degradation of protochlorophyllide esters, i.e., protochlorophylls, were studied in etiolated leaves of kidney bean in relation to their aging. By the sensitive analysis of the pigments using high-performance liquid chromatography, the presence of four protochlorophylls esterified with phytol, tetrahydrogeranylgeraniol (THGG), dihydrogeranylgeraniol (DHGG), and geranylgeraniol (GG) was detected in kidney bean grown in the dark. Similar components were also observed in the etiolated seedlings of cucumber, sunflower, and corn. The content of each protochlorophyll species changed with the plant species and age of plants. In the case of kidney bean, the content of protochlorophyll phytol reached a maximal level at 9 days, then decreased rapidly during the subsequent development, in spite of the total protochlorophyll content remaining unchanged. In contrast to the degradation of protochlorophyll phytol, the other three protochlorophylls esterified with THGG, DHGG, and GG accumulated. These results may indicate that (i) protochlorophyll phytol is formed from the first esterified protochlorophyll GG through the next three hydrogenation steps as in the case of chlorophyll a phytol formation; (ii) the esterification reaction stops at 9 days and then reaction proceeds in sequence in the reverse direction, leading to the dehydrogenation of the alcohol moiety of protochlorophyll phytol to protochlorophylls THGG, DHGG, and GG.

Purification by affinity chromatography and properties of uroporphyrinogen I synthetase from Chlorella regularis

Uroporphyrinogen I synthetase (porphobilinogen ammonia-lyase (polymerizing), EC 4.3.1.8) from Chlorella regularis was purified to homogeneity by affinity chromatography on porphobilinogen-AH-Sepharose 4B, which was prepared by reacting carbodiimide with substrate, porphobilinogen. The enzyme was purified 232-fold from the initial crude extract and specific activity was 348 nmol porphyrinogen I formed (mg protein)-1 . h-1 at pH 7.4. The molecular weight of the enzyme was 35 000-36 000 as determined by Sephadex G-100 gel filtration. This enzyme was acidic protein having an isoelectric point of 4.2. The enzyme exhibited a single pH optimum at a pH value of 7.4 both in phosphate and Tris-HCl buffer. The Km value for porphobilinogen was 89 microM as measured by its consumption and 85 microM when uroporphyrin formation was used. The Arrhenius plot obtained from the enzyme activity measurements appeared triphasic with breaks occurring at 35 and 46 degrees C and activation energy was calculated to be 21 700 (10-35 degrees C), 12 700 (35-46 degrees C) and 1800 cal . mol-1 (46-65 degrees C). This enzyme was heat stable and the enzyme still retained 87% of activity, even after 1 h incubation at 75 degrees C.

Light-induced oxidation-reduction reactions of cytochromes in the green sulfur photosynthetic bacterium Prosthecochloris aesturarii

The light-induced oxidation-reduction reactions of cytochromes in intact cells, starved cells, and chlorobium vesicle fractions of the green sulfur photosynthetic bacterium Prosthecochloris aesturarii were studied under anaerobic conditions. On the basis of both kinetic and spectral properties, at least three cytochrome species were found to be involved in the light-induced oxidation-reduction reactions of intact cells. These cytochromes were designated according to the positions of alpha-band maxima as C555 (rapid and slow components) and C552 (intermediate). By comparing the light-minus-dark difference spectra with the reduced-minus-oxidized difference spectra of purified cytochromes of this organism, rapid component C555 and intermediate component C552 are suggested to correspond to the purified cytochromes c-555(550) and c-551.5, respectively. Although the identity of the slow-phase component is uncertain, one possibility is that the slow phase is due to the bound form of c-555(550). In substrate-depleted (starved) cells, only one cytochrome species, C555 remained in the reduced state in the dark and oxidized upon actinic illumination. This corresponds to the rapid C555 component in intact cells. In the case of chlorobium vesicle fractions, one cytochrome species having an alpha-band maximum at 554 nm was oxidized by actinic light. The effects of several inhibitors on the absorbance changes of intact cells were studied. Antimycin A decreased the rate of the dark reduction of rapid C555 component. The complex effects of CCCP (carbonyl cyanide m-chlorophenylhydrazone) on the oxidation-reduction reactions of cytochromes were interpreted as the results of inhibition of the electron donation to oxidized C552 and C555 (slow), and a shift of the dark steady-state redox levels of cytochromes. Based on these findings, it is suggested that the rapid C555 component is located in a cyclic electron transfer pathway. The other two cytochromes, C552 and C555 (slow), may be located in non-cyclic electron transfer pathways and receive electrons from exogenous substrates such as sodium sulfide. A tentative scheme for the electron transfer system in Prosthecochloris aestuarii is presented and its nature is discussed.

Isolation and some properties of NAD+ reductase of the green photosynthetic bacterium Prosthecochloris aestuarii

NAD+ reductase of the green photosynthetic bacterium Prosthecochloris aestuarii was isolated and purified by ammonium sulfate fractionation, DEAE-cellulose column chromatography, and Sephadex G-200 gel filtration. This enzyme is an FAD-containing flavoprotein and has absorption maxima at 485 (shoulder0 452, 411, and 385 nm (the 411 nm band is due to cytochrome). The molecular weight of the enzyme as determined by gel filtration using Sephadex G-200 is 119,000. The enzyme catalyzes the reduction of NAD+ and NADP+ by photoreduced spinach ferredoxin or reduced benzyl viologen...