Studies on a wide-spectrum intestinal dipeptide uptake system in the monkey and in the human

1. The intestinal transport of glycine and leucine residues of glycyl-L-leucine was studied in the monkey and in the human in vitro. Uptake of both [14C]glycyl-L-leuine and glycyl-L-[14C]leucine show similar Kt values, but there is a marked difference in the Vmax. values. Preliminary studies suggest that this anomalous difference in the Vmax. values may be due to the greater efflux rate of glycine from the tissue. 2. Arrhenius plots of both [14C]glycyl-L-leucine uptake and glycyl-L-[14C]leucine uptake in the monkey intestine show a discontinuity at about 20 degrees C. The activation energies above and below the discontinuity are similar for both [14C]glycyl-L-leucine uptake and glycyl-L-[14C]leucine uptake. These similarities in uptake characteristics suggest that the dipeptide glycyl-L-leucine is transported as one unit. 3. In the monkey intestine, glycyl-L-leucine uptake is inhibited by a wide variety of dipeptides, including those containing acidic and basic amino acids. The inhibition was shown to be competitive by using four representative dipeptides namely: L-alanyl-L-alanine, L-alanyl-L-leucine, L-glutamyl-L-glutamic acid and L-lysyl-L-lysine. The results strongly suggest that in the monkey intestine there may be a dipeptide-uptake system with an extremely broad specificity. These results were also confirmed in the human in a limited way.

Thio derivatives of β-diketones and their metal chelates. XVIII. Mass spectra of some metal chelates of the monothio derivatives of benzoylacetone anddibenzoylmethane

The mass spectra of the iron(III), cobalt(III), nickel(II) and zinc(II) complexes of the monothio-β-diketones RC(SH)=CHCOPh (R = Me, Ph) have been obtained. The iron and cobalt complexes of 3-mercapto-1-phenylbut- 2-en-1-one (R = Me) do not give a peak for the molecular ion due to thermal degradation to the bivalent metal complex Met(MeCS=CHCOPh)2 (Met = Fe, Co), which then undergoes reactions similar to those undergone by the nickel and zinc complexes. The most interesting feature of the spectra is the loss of hydrogen sulphide which does not occur with the free ligand or with metal complexes of fluorinated monothio-8-diketones RC(SH)=CHCOCF3. ��� The zinc complex of 3-mercapto-1,3-diphenylprop-2-en-1-one (R = Ph) undergoes fragmentation in the mass spectrometer to produce inter alia [ZnC6H5]+. However, the iron(III), cobalt(III), nickel(II) and palladium(II) complexes undergo thermal degradation in the mass spectrometer but the mass spectra of these four complexes give metal-free ions with m/e greater than m/e for L, due to fragmentation of the ion 2L.

Mass spectral studies of lanthanide chelates. I. Samarium, europium, gadolinium and terbium chelates of thenoyltrifluoroacetone

The mass spectra of the lanthanide chelates of thenoyltrifluoroacetone, viz. Met{CF3COCH=C(O-)-C4H3S}3 (Met = Sm, Eu, Gd, Tb), have been obtained. All four spectra display similar fragmentation patterns. Fluorine migration to the metal with the concomitant loss of :CF2 occurs with all four lanthanide chelates. Peaks were observed for the ions [MetF2]+ (Met = Sm, Gd, Tb) and [MetF]+ (Met = Sm, Eu). The occurrence of [MetF]+ in the spectra of the samarium and europium chelates is in keeping with the tendency of these two lanthanides to be reduced to the bivalent state. On the other hand, oxidation of terbium(III) to terbium(IV) was not observed in the mass spectra.

A comparative study of the distribution of soluble and particulate glycyl-L-leucine hydrolase in the small intestine

1. A comparative study has been made of glycyl-l-leucine hydrolase activity in the soluble and particulate fractions of intestinal mucosa from monkey, guinea-pig, rabbit and rat. The specific activity of the soluble enzyme is very high in monkey and guinea-pig, and lower in rabbit and rat. The particulate enzymes from all the four species show low specific activities and form 1–10% of the total activity.

2. The pH optima in all cases lie in the range 7·6–7·8. The Km values of the substrate were similar for both soluble and particulate enzyme from monkey and guinea-pig, but in the rabbit and rat the Km value with the particulate enzyme was higher than with the soluble enzyme.

3. The particulate enzyme activity in all cases was the highest in the distal regions of the intestine, whereas the soluble enzyme showed maximal activity in the proximal and middle regions.

Thio derivatives of β-Diketones and their metal chelates. XV. Mass spectra of cobalt(III) and rhodium(III) chelates of some fluorinated Monothio-β-diketones

The mass spectra of the cobalt(111) and rhodium(111) chelates of the fluorinated monothio-β-diketones RC(SH)=CHCOCF3 (R = Ph, p-MeC6H4, p-BrC6H4, p-FC6H4, and 2-thienyl) and of the cobalt(111) chelate of CH3C(SH)=CHCOCF3 have been obtained. The cobalt chelates do not give a peak for the molecular ion because of thermal degradation to the cobalt(11) complex CO(RCS=CHCOCF3)2, which then undergoes reactions in the mass spectrometer. Fluorine migration occurs with cobalt but not with rhodium. The cobalt complexes give rise to more metal-containing fragments than their rhodium analogues. Mechanisms are proposed for the reactions involving the metal-containing fragments. Cobalt undergoes valency changes to give cobalt(11) and cobalt(1) complex ions, whereas rhodium undergoes a valency change to the bivalent state only.

Thio derivatives of β-diketones and their metal chelates. XIV. Mass spectra of palladium and platinum chelates of some fluorinated Monothio-β-diketones

The mass spectra of the palladium(11) and platinum(11) chelates of the fluorinated monothio-β- diketones, RC(SH)=CHCOCF3 (R = Ph, p-MeC6H4, p-BrC6H4, p-NO2C6H4, 2-thienyl), and of the palladium chelate of CH3C(SH)=CHCOCF3 have been obtained. The platinum chelates give rise to more metal-containing peaks than the palladium chelates. Mechanisms are proposed for the reactions involving the metal-containing fragments. A comparison of the mass spectra of the zinc, nickel, palladium and platinum chelates of these fluorinated monothio-β-diketones reveals that the fragmentation pattern is determined by the metal.

Hydrolysis of Monothio-β-diketones. II. Hydrolysis of three fluorinated Monothio-β-diketones

The rapid decomposition of the fluorinated monothio-β-diketones RC(SH)=CHCOCF3, 4-(3?-bromophenyl)-1,1,1-trifluoro-4-mercaptobut-3-en-2- one (R = m-BrC6H4), 4-(4?-bromophenyl)-1,1,1-trifluoro-4-mercaptobut-3- en-2-one (R = p-BrC6H4) and 1,1,1-trifluoro-4-mercaptopent-3-en-2-one(R = Me), in acid solution has been shown to occur by hydrolytic cleavage to yield the ketone RCOCH3, hydrogen sulphide and probably trifluoroacetic acid. The pseudo first-order rate constants for these compounds are (8.0�0.3)x 10-3, min-1, (6.0 � 0.6) x 10-3 min-1 and 0.12�0.01 min-1, respectively. The greater vulnerability of 1,1,1- trifluoro-4-mercaptopent-3-en-2-one, compared to the other two monothio-β-diketones, towards hydrolytic cleavage is related to the nature of the R substituent in that conjugation involving the terminal aromatic ring stabilizes the monothio-β-diketone.

Thio derivatives of β-Diketones and their metal chelates. XVII. Mass spectra of iron(III) and ruthenium(III) chelates of some fluorinated Monothio-β-diketones

The mass spectra of the iron(111) and rhodium(111) chelates of the fluorinated monothio-β-diketones RC(SH)=CHCOCF3 (R = Ph,p-MeC6H4, 2-thienyl) have been obtained. Whereas the ruthenium(111) chelates give a peak for the molecular ion, the iron(111) chelates do not, due to thermal degradation to the iron(11) complex Fe(RCS=CHCOCF3)2 which then undergoes reactions in the mass spectrometer. Fluorine migration occurs with two of the iron chelates but not with the ruthenium chelates. Mechanisms are proposed for the reactions of the ruthenium chelates.

Thio derivatives of b-diketones and their metal chelates. XIII. Mass spectra of zinc and nickel chelates of some fluorinated monothio-b-diketones

The mass spectra of the zinc(11) and nickel(11) chelates of four fluorinated monothio-β-diketones, RC(SH)=CHCOCF3 (R = Ph, p-MeC6H4, 2-thienyl, Me), have been obtained. The mass spectra of the nickel chelates have considerably more peaks due to metal-containing species than the spectra of the zinc chelates, while the reverse is true for the metal-free fragments. All the zinc chelates give peaks for M (molecular ion), M ? CF3, M - L (LH = monothio-β-diketone), M - L ? CF2, LH, L, L - F, RCSCH and RCS. All the nickel chelates give peaks for M, M - F, M ? CF3, M - COCF3, M - L, M- 2L and L. In addition, some of the metal chelates give other peaks. Mechanisms are proposed for the reactions giving rise to some of these species. All the zinc and nickel chelates give a strong peak due to L+ arising from a valence change of the metal ion from the bivalent to the univalent state as follows: [Me11L2]+ → L+ + Me1L (Me = Zn, Ni). It is suggested that the ion L+ has a resonance-stabilized cyclic structure.

Thio derivatives of β-diketones and their metal chelates. XVI. Nickel(II), palladium(II), platinum(II), zinc(II) and cobalt(III) chelates of some new fluorinated Monothio-β-diketones

The new fluorinated β-diketones RCOCH2COCF3 (R = p-ClC6H4, m-ClC6H4, m-BrC6H4, m-MeC6H4 and m,p-C1,C6H3) have been prepared. The monothio-β-diketones RC(SH)=CHCOCF3 derived from these β-diketones were also prepared. Complexes of these monothio-β-diketones and of p-FC6H4C(SH)=CHCOCF3 with nickel(11), palladium(11), platinum(11), zinc(11) and coba1t(111) have been prepared and characterized. All the complexes are stable and display sharp melting points.

Glycyl-L-leucine hydrolase, a versatile 'master' dipeptidase from monkey small intestine

1. A highly active and electrophoretically homogeneous dipeptidase was purified from the soluble extracts of monkey small-intestinal mucosa. 2. By gel-filtration studies the molecular weight of the enzyme was found to be 107000. It is composed of two identical, subunits of molecular weight 54000. 3. A paper-chromatographic method of dipeptidase assay was developed to overcome some of the difficulties encountered in the generally used spectrophotometric procedure. By using this method, the K(m) and k(0) values of a few substrates were determined. 4. The substrate specificity of the enzyme was investigated in great detail with substrates of a wide range of possible structural types. The enzyme hydrolyses a very large proportion of the range of dipeptides tested. This enzyme, which exhibits such a wide range of action, has been termed the ;master' dipeptidase of the intestine. Glycylglycine, glycyl-l-proline, glycyl-l-histidine, l-prolylglycine and some of the arginine- and aspartic acid-containing dipeptides were not substrates and are possibly hydrolysed by other peptidases. These results therefore suggest that in the intestine the number of dipeptidases is rather limited. 5. In the light of these findings, the implications on the role of dipeptidases in intestinal peptide transport are discussed.

SERO-PREVALENCE OF INFECTIOUS BRONCHITIS IN CHICKEN IN BANGLADESH

The investigation was conducted to detect infectious bronchitis (IB) virus-specific antibody in chicken from some selected areas of Bangladesh. The indirect enzyme linked immunosorbent assay (iELISA) was performed to estimate the infectious bronchitis virus specific antibody. In case of sera-samples collected from BRAC diagnostic laboratory, Gazipur, 100% sera samples were found to be positive to IBV; the highest antibody titres were recorded as 9867.29. The average antibody titre of samples from Anis Poultry Farm, Pabna and farms driven by beneficiary of SDC, Faridpur and layer chickens reared with the help of BEES, Hobigonj were recorded as 1234.38, 1076.94 and 4572.85 and percent of sero-positive cases were 56.67%, 43.33% and 92.50% respectively. In this study all breeds of chicken (non descriptive indigenous and commercial) and age groups were found equally susceptible to IB.

Red drop in the quantum yield of fluorescence of sonicated algae

The change of the quantum yield of fluorescence, Phi, with the frequency of exciting light, was investigated in Chlorella, Anacystis, and Porphyridium suspensions, and in sonicates from these cells prepared under aerobic and anaerobic conditions. In case of Chlorella, sonicates were made in acid and in alkaline media (pH 4.65 and 7.80). In the alkaline medium, a drop of Phi towards the longer waves was found to begin at 1.466 x 10(4) cm(-1) (682 nm) in sonicates, and in suspension. In the acid medium, the drop began at 1.471 x 10(4) cm(-1) (680 nm), 1.418 x 10(4) cm(-1) (705 nm), and 1.389 x 10(4) cm(-1) (720 nm) in suspension, anaerobic sonicate, and aerobic sonicate, respectively. The results indicate that the cause of the change in the red drop is preferential destruction of a long-wave component of chlorophyll a (such as Chl a 693). The amount of this component remaining after sonication is larger in alkaline than in acid sonicates. With Anacystis and Porphyridium, only alkaline suspensions (pH 7.80) could be used for sonication, because in acid medium, the phycobilin-chlorophyll complex is rapidly broken and phycobilin extracted from the cell. In Anacystis, the red drop begins at 1.562 x 10(4) cm(-1) (640 nm) and 1.538 x 10(4) cm(-1) (650 nm) in suspension and sonicate, respectively; in Porphyridium, it starts at 1.550 x 10(4) cm(-1) (645 nm) in both cases. These results suggest that sonication in alkaline medium (pH 7.80) destroys some Chl a 693 in Anacystis, but not in Porphyridium.