Solvent and kinetic isotope effects in the reaction of oxidative deamination of L-alanine, catalyzed by L-alanine dehydrogenase, AIaDH, （EC 1.4.1.1） were determined using a non-competitive spectroscopic method. The ...Solvent and kinetic isotope effects in the reaction of oxidative deamination of L-alanine, catalyzed by L-alanine dehydrogenase, AIaDH, （EC 1.4.1.1） were determined using a non-competitive spectroscopic method. The progress of the reaction was monitored spectrophotometrically by measuring the increasing absorbance of the reduced form of NADH at 340 nm. L-alanine, stereospecifically labeled with deuterium was synthesized by enzymatic reductive amination of pyruvate in presence of [（4R）-2H]-NADH, which was obtained by deuterium transfer from deuteriated formic acid to NAD~ catalyzed by FDH （formate dehydrogenase） （EC 1.2.1.2）. [2-2H]-L-alanine, the product of enzymatic synthesis catalyzed by AIaDH, was obtained with 75% deuterium enrichment and values of isotopic effects were approximated to the values corresponding to 100% of deuterium incorporation. The enzyme AIaDH isolated from Bacillus subtilis shows pro-R stereospecificity, what indicates that hydrogen is exclusively transferred from pro-R position at C-4 of the nicotinamide ring of NADH to C-2 of pyruvate to form L-alanine. Some intrinsic mechanistic details of enzymatic oxidative deamination of L-alanine were discussed using determined numerical values of kinetic and solvent isotope effects on Vmax and Vmax,│KM展开更多
A new complex [Cu2（sala）2（H20）2（4,4＇-bipy）]＇H20 （sala = N-（2-hydroxybenzyl）- D,L-alaninate, 4,4＇-bipy = 4,4＇-bipyridine） has been synthesized and characterized by elemental analysis, IR spectroscopy, the...A new complex [Cu2（sala）2（H20）2（4,4＇-bipy）]＇H20 （sala = N-（2-hydroxybenzyl）- D,L-alaninate, 4,4＇-bipy = 4,4＇-bipyridine） has been synthesized and characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis and single-crystal X-ray diffraction. The complex crystallizes in monoclinic system, space group C2/c with a = 42.44（3）, b = 10.416（8）, c = 15.487（13） ./k, fl = 97.455（14）°, C30H36Cu2N4O9, Mr = 723.71, V = 6789（9） A3, Dc = 1.416 g/cm3, Z = 8, F（000） = 2992, μ（MoKa） = 1.308 mm-1, R = 0.0493 and wR = 0.1004 for 4878 observed reflections （I 〉 2σ（I））. Structural analysis shows that each copper（II） atom displays a distorted square-based pyramidal coordination geometry with two oxygen atoms and one nitrogen atom from one N-（2-hydroxybenzyl）-D,L-alaninate, one nitrogen atom from 4,4＇-bipyridine ligand and one water molecule. 4,4＇-Bipyridine ligand bridges two Cu（II） ions to form a dinuclear compound. The molecular structure is extended into a one-dimensional wavy chain through hydrogen bonds. These 1D chains are further expanded into 2D networks through hydrogen bonds.展开更多
One new chiral zeolitic rho-type metal-organic framework [Cd（L-ala）2]n（1） has been successfully synthesized based on L-alanine chiral ligand, which demonstrates the feasibility of fabricating MOF that integrates t...One new chiral zeolitic rho-type metal-organic framework [Cd（L-ala）2]n（1） has been successfully synthesized based on L-alanine chiral ligand, which demonstrates the feasibility of fabricating MOF that integrates the 4-connected zeotype topology by the employment of L-alanine. To the best of knowledge, it’s the first report that metal-organic framework based on amino acid features the chiral zeolitic rho-type structure. Compound 1 was characterized by X-ray powder diffraction, elemental analysis and single-crystal X-ray diffraction. Crystal data: C6 H9 CdN2 O4, Mr = 285.55, cubic system, space group I432, a = 24.0795（6）, V = 13961.9（10） ?3, Z = 48, Dc = 1.630 Mg/m3, F（000） = 6672, μ（Mo Kα） = 1.865 mm-1, S = 1.058, R = 0.0271 and wR = 0.0312 for 1870 observed reflections with I > 2σ（I）. The circular dichroism（CD） property of compound 1 was also investigated.展开更多
Different amino acids have been shown to affect feed intake when injected directly into the central nervous system of birds. In the present study, we investigated the effects of L-glutamine and L-alanine on feed intak...Different amino acids have been shown to affect feed intake when injected directly into the central nervous system of birds. In the present study, we investigated the effects of L-glutamine and L-alanine on feed intake and the mRNA expression levels of hypothalamic neuropeptides involved in feed intake regulation in broiler chicks. L-Glutamine or L- alanine was intra-cerebroventricularly （ICV） administered to 4-d-old broiler chicks and the feed intake were recorded at various time points. Quantitative PCR was performed to determine the hypothalamic mRNA expression levels of neuropeptide Y （NPY）, agouti related protein （AgRP）, pro-opiomelanocortin （POMC）, melanocortin receptor 4 （MC4R） and corticotropin releasing factor （CRF）. Our results showed that ICV administration of L-glutamine （0.55 or 5.5 pmol） significantly increased feed intake up to 2 h post-administration period and the hypothalamic NPY mRNA expression levels, while it markedly decreased hypothalamic POMC and CRF mRNA expression levels. In contrast, ICV administration of L-alanine （4 lamol） significantly decreased feed intake for the first 0.5 h post-administration period, and reduced the hypothalamic AgRP mRNA expression levels, while it remarkablely enhanced the mRNA expression levels of MC4R and CRF. These findings suggested that L-glutamine and L-alanine could act within the hypothalamus to influence feed intake in broiler chicks, and that both orexigenic and anorexigenic neuropeptide genes might contribute directly to these effects.展开更多
L-Serine is considered a functional amino acid in the central nervous system, and induces sedation and hypnotic effects in some animal models of acute and chronic stress. Accordingly, while L-serine is a candidate ant...L-Serine is considered a functional amino acid in the central nervous system, and induces sedation and hypnotic effects in some animal models of acute and chronic stress. Accordingly, while L-serine is a candidate anti-stress factor, the central mechanism of L-serine is not clear. The present study clarifies the action of L-serine using acute chick brain slices. We investigated the changes in some extracellular fluid amino acid concentrations in response to L-serine perfusion. Taurine concentration decreased while L-alanine concentration increased following L-serine perfusion. To examine the involvement of the taurine transporter, the effect of L-serine on the taurine concentration in the presence and absence of Na+ was also investigated. Na+ had no effect on taurine concentration induced by L-serine perfusion. These results suggest that L-serine has an ability to promote L-alanine synthesis facilitating the catabolism of taurine. In conclusion, L-serine modifies the metabolism of taurine and L-alanine in the extracellular space in chick brain.展开更多
Biochirality originates from the chiral influences in the universe. The parity non-conservation of weak neutral current, which takes place through the exchange of neutral boson Z0 combined with the long range Coulomb ...Biochirality originates from the chiral influences in the universe. The parity non-conservation of weak neutral current, which takes place through the exchange of neutral boson Z0 combined with the long range Coulomb interaction in atoms and molecules, produces a parity violating energy difference (PVED). In this note, the fact is to be indicated that there is a λ -type second order phase transition of D- and L-alanine (valine) at a certain critical temperature Tc. The PVED is to be calculated as 6×10-5 eV/molecule by varieties of modern physical and chemical methods including the differential scanning calorimeter (DSC), SQUID, single crystal X-ray diffraction spectra, low-temperature 1H-MAS ssNMR, Raman spectra and ultrasonic measurement. A mechanism that differs from Salam’s hypotheses is also discussed here.展开更多
By using the corresponding L-amino acid sodium as initiator,ε-caprolactone-depsipeptides CL-Ala and CL-Leu were prepared by the reactions ofε-caprolactone(CL)with L-alanine and L-leucine,respec-tively,and p-dioxanon...By using the corresponding L-amino acid sodium as initiator,ε-caprolactone-depsipeptides CL-Ala and CL-Leu were prepared by the reactions ofε-caprolactone(CL)with L-alanine and L-leucine,respec-tively,and p-dioxanone-depsipeptide(PDO-Leu)was prepared by the reaction of p-dioxanone(PDO)with L-leucine.Two poly(ε-caprolactone)oligomers(PCL-Ala and PCL-Leu)of different molecular weights with depsipeptide unit were synthesized by controlling the feed ratio of L-amino acid sodium and CL.The presence of the depsipeptide structure in these obtained products was confirmed by 1H NMR spectra and the molecular weight of the poly(ε-caprolactone)oligomers was measured by gel permeation chromatography(GPC).These products con-tain a hydroxyl group and a carboxyl group in one molecule,which means they could act as bifunctional monomers for further polymerization to prepare high molecular weight polymers.By this way,the depsipeptide unit could be introduced into the polymers and the biodegradation rates of the novel polymers could be well controlled in vivo by the tailored molecular structures.展开更多
文摘Solvent and kinetic isotope effects in the reaction of oxidative deamination of L-alanine, catalyzed by L-alanine dehydrogenase, AIaDH, （EC 1.4.1.1） were determined using a non-competitive spectroscopic method. The progress of the reaction was monitored spectrophotometrically by measuring the increasing absorbance of the reduced form of NADH at 340 nm. L-alanine, stereospecifically labeled with deuterium was synthesized by enzymatic reductive amination of pyruvate in presence of [（4R）-2H]-NADH, which was obtained by deuterium transfer from deuteriated formic acid to NAD~ catalyzed by FDH （formate dehydrogenase） （EC 1.2.1.2）. [2-2H]-L-alanine, the product of enzymatic synthesis catalyzed by AIaDH, was obtained with 75% deuterium enrichment and values of isotopic effects were approximated to the values corresponding to 100% of deuterium incorporation. The enzyme AIaDH isolated from Bacillus subtilis shows pro-R stereospecificity, what indicates that hydrogen is exclusively transferred from pro-R position at C-4 of the nicotinamide ring of NADH to C-2 of pyruvate to form L-alanine. Some intrinsic mechanistic details of enzymatic oxidative deamination of L-alanine were discussed using determined numerical values of kinetic and solvent isotope effects on Vmax and Vmax,│KM
基金supported by the Science and Technology Research Project of Key Laboratory of Higher Institutions of Jiangxi Province(No.GJJ10732)the Science and Technology Research Projects of the Education Department of Jiangxi Province(No.GJJ10608)+1 种基金the Research Fund of Shangrao Normal University(No.0807)Fourth point of Specialty Construction College of Education Ministry(No.TS11524)
文摘A new complex [Cu2（sala）2（H20）2（4,4＇-bipy）]＇H20 （sala = N-（2-hydroxybenzyl）- D,L-alaninate, 4,4＇-bipy = 4,4＇-bipyridine） has been synthesized and characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis and single-crystal X-ray diffraction. The complex crystallizes in monoclinic system, space group C2/c with a = 42.44（3）, b = 10.416（8）, c = 15.487（13） ./k, fl = 97.455（14）°, C30H36Cu2N4O9, Mr = 723.71, V = 6789（9） A3, Dc = 1.416 g/cm3, Z = 8, F（000） = 2992, μ（MoKa） = 1.308 mm-1, R = 0.0493 and wR = 0.1004 for 4878 observed reflections （I 〉 2σ（I））. Structural analysis shows that each copper（II） atom displays a distorted square-based pyramidal coordination geometry with two oxygen atoms and one nitrogen atom from one N-（2-hydroxybenzyl）-D,L-alaninate, one nitrogen atom from 4,4＇-bipyridine ligand and one water molecule. 4,4＇-Bipyridine ligand bridges two Cu（II） ions to form a dinuclear compound. The molecular structure is extended into a one-dimensional wavy chain through hydrogen bonds. These 1D chains are further expanded into 2D networks through hydrogen bonds.
基金supported financially by National Natural Science Foundation of China(No.21601080)
文摘One new chiral zeolitic rho-type metal-organic framework [Cd（L-ala）2]n（1） has been successfully synthesized based on L-alanine chiral ligand, which demonstrates the feasibility of fabricating MOF that integrates the 4-connected zeotype topology by the employment of L-alanine. To the best of knowledge, it’s the first report that metal-organic framework based on amino acid features the chiral zeolitic rho-type structure. Compound 1 was characterized by X-ray powder diffraction, elemental analysis and single-crystal X-ray diffraction. Crystal data: C6 H9 CdN2 O4, Mr = 285.55, cubic system, space group I432, a = 24.0795（6）, V = 13961.9（10） ?3, Z = 48, Dc = 1.630 Mg/m3, F（000） = 6672, μ（Mo Kα） = 1.865 mm-1, S = 1.058, R = 0.0271 and wR = 0.0312 for 1870 observed reflections with I > 2σ（I）. The circular dichroism（CD） property of compound 1 was also investigated.
基金the National Basic Research Program of China (2009CB941601)the Joint Funds of the National Natural Science Foundation of China (u0731004)+3 种基金the National Natural Science Foundation of China(30871845, 30901058 and 30972157)the Natural Science Foundation of Guangdong Province of China(9451064201003790 and 9151064201000056)the National Public Benefit (Agricultural) Research Foundation of China(201003011)the Specialized Research Fund for the Doctoral Program of Higher Education of China(20094404120012)
文摘Different amino acids have been shown to affect feed intake when injected directly into the central nervous system of birds. In the present study, we investigated the effects of L-glutamine and L-alanine on feed intake and the mRNA expression levels of hypothalamic neuropeptides involved in feed intake regulation in broiler chicks. L-Glutamine or L- alanine was intra-cerebroventricularly （ICV） administered to 4-d-old broiler chicks and the feed intake were recorded at various time points. Quantitative PCR was performed to determine the hypothalamic mRNA expression levels of neuropeptide Y （NPY）, agouti related protein （AgRP）, pro-opiomelanocortin （POMC）, melanocortin receptor 4 （MC4R） and corticotropin releasing factor （CRF）. Our results showed that ICV administration of L-glutamine （0.55 or 5.5 pmol） significantly increased feed intake up to 2 h post-administration period and the hypothalamic NPY mRNA expression levels, while it markedly decreased hypothalamic POMC and CRF mRNA expression levels. In contrast, ICV administration of L-alanine （4 lamol） significantly decreased feed intake for the first 0.5 h post-administration period, and reduced the hypothalamic AgRP mRNA expression levels, while it remarkablely enhanced the mRNA expression levels of MC4R and CRF. These findings suggested that L-glutamine and L-alanine could act within the hypothalamus to influence feed intake in broiler chicks, and that both orexigenic and anorexigenic neuropeptide genes might contribute directly to these effects.
文摘L-Serine is considered a functional amino acid in the central nervous system, and induces sedation and hypnotic effects in some animal models of acute and chronic stress. Accordingly, while L-serine is a candidate anti-stress factor, the central mechanism of L-serine is not clear. The present study clarifies the action of L-serine using acute chick brain slices. We investigated the changes in some extracellular fluid amino acid concentrations in response to L-serine perfusion. Taurine concentration decreased while L-alanine concentration increased following L-serine perfusion. To examine the involvement of the taurine transporter, the effect of L-serine on the taurine concentration in the presence and absence of Na+ was also investigated. Na+ had no effect on taurine concentration induced by L-serine perfusion. These results suggest that L-serine has an ability to promote L-alanine synthesis facilitating the catabolism of taurine. In conclusion, L-serine modifies the metabolism of taurine and L-alanine in the extracellular space in chick brain.
基金This research was supported by the "863" program (Grant No. 863-103-13-06-01).
文摘Biochirality originates from the chiral influences in the universe. The parity non-conservation of weak neutral current, which takes place through the exchange of neutral boson Z0 combined with the long range Coulomb interaction in atoms and molecules, produces a parity violating energy difference (PVED). In this note, the fact is to be indicated that there is a λ -type second order phase transition of D- and L-alanine (valine) at a certain critical temperature Tc. The PVED is to be calculated as 6×10-5 eV/molecule by varieties of modern physical and chemical methods including the differential scanning calorimeter (DSC), SQUID, single crystal X-ray diffraction spectra, low-temperature 1H-MAS ssNMR, Raman spectra and ultrasonic measurement. A mechanism that differs from Salam’s hypotheses is also discussed here.
基金financially supported by Program for the New Century Excellent Talents in University“NCET”,Ministry of Education of China,and by the International Cooperation from Ministry of Science and Technology of China(Grant No.2008DFA51170)sponsored by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,Ministry of Education of China.
文摘By using the corresponding L-amino acid sodium as initiator,ε-caprolactone-depsipeptides CL-Ala and CL-Leu were prepared by the reactions ofε-caprolactone(CL)with L-alanine and L-leucine,respec-tively,and p-dioxanone-depsipeptide(PDO-Leu)was prepared by the reaction of p-dioxanone(PDO)with L-leucine.Two poly(ε-caprolactone)oligomers(PCL-Ala and PCL-Leu)of different molecular weights with depsipeptide unit were synthesized by controlling the feed ratio of L-amino acid sodium and CL.The presence of the depsipeptide structure in these obtained products was confirmed by 1H NMR spectra and the molecular weight of the poly(ε-caprolactone)oligomers was measured by gel permeation chromatography(GPC).These products con-tain a hydroxyl group and a carboxyl group in one molecule,which means they could act as bifunctional monomers for further polymerization to prepare high molecular weight polymers.By this way,the depsipeptide unit could be introduced into the polymers and the biodegradation rates of the novel polymers could be well controlled in vivo by the tailored molecular structures.
