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Bragg PD, Hou C. Ligand-induced conformational changes in the Escherichia coli F1 adenosine triphosphatase probed by trypsin digestion. BIOCHIMICA ET BIOPHYSICA ACTA 1987; 894:127-37. [PMID: 2890377 DOI: 10.1016/0005-2728(87)90182-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Digestion of the F1-ATPase of Escherichia coli with trypsin stimulated ATP hydrolytic activity and removed the delta and epsilon subunits of the enzyme. A species represented by the formula alpha 1(3) beta 1(3) gamma 1, where alpha 1, beta 1 and gamma 1 are forms of the native alpha, beta and gamma subunits which have been attacked by trypsin, was formed by trypsin digestion in the presence of ATP. In the presence of ATP and MgCl2, conversion of gamma to gamma 1 was retarded and the enzyme retained the epsilon subunit. These results imply that binding of ATP to the beta subunits alters the conformation of ECF1 to increase the accessibility of the gamma subunit to trypsin. The likely trypsin cleavage sites in the alpha, beta and gamma subunits are discussed. ECF1 from the alpha subunit-defective mutant uncA401, or after treatment with N,N'-dicyclohexylcarbodiimide or 4-chloro-7-nitrobenzofurazan, was present in a conformation in which the gamma subunit was readily accessible to trypsin and could not be protected by the presence of ATP and MgCl2. In a similar manner to native E. coli F1-ATPase, the hydrolytic activity of the trypsin-digested enzyme was stimulated by the detergent lauryldimethylamine N-oxide. Since the digested enzyme lacked the epsilon subunit, a putative inhibitor of hydrolytic activity, a mechanism for the stimulation which involves loss or movement of this subunit is untenable.
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227
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Bragg PD, Hou C. Effect of disulfide cross-linking between alpha and delta subunits on the properties of the F1 adenosine triphosphatase of Escherichia coli. BIOCHIMICA ET BIOPHYSICA ACTA 1986; 851:385-94. [PMID: 2875734 DOI: 10.1016/0005-2728(86)90075-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Under very mild oxidizing conditions the delta subunit of the F1-ATPase of Escherichia coli can be crosslinked by a disulfide linkage to one of the alpha subunits of the enzyme. The cross-linked ATPase resembles the native enzyme in the following properties: specific activity; activation by lauryldimethylamine N-oxide (LDAO); binding of aurovertin D and ADP; cross-linking products with 3,3'-dithiobis(succinimidyl propionate); binding to ATPase-stripped everted membrane vesicles and the N,N'-dicyclohexylcarbodiimide sensitivity of the rebound enzyme. However, the rebound crosslinked ATPase differed from the native enzyme in lacking the ability to restore NADH oxidation - and ATP hydrolysis-dependent quenching of the fluorescence of quinacrine to ATPase-stripped membrane vesicles. It is proposed that the delta subunit is involved in the proton pathway of the ATPase, and that this pathway is affected in the alpha delta-cross-linked enzyme. The mechanism for activation of the ATPase by LDAO was examined. Evidence against the proposal of Lötscher, H.-R., De Jong, C. and Capaldi, R.A. (Biochemistry (1984) 23, 4140-4143) that activation involves displacement of the epsilon subunit from an active site on a beta subunit was obtained.
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228
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Li WG, Gong HM, Xie JR, Yu SY, Zhu YJ, Gong XL, Hou C, Wu B, Cao LS. [Regional distribution of liver cancer and its relation to selenium levels in Qidong County, China]. ZHONGHUA ZHONG LIU ZA ZHI [CHINESE JOURNAL OF ONCOLOGY] 1986; 8:262-4. [PMID: 3757738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The selenium (Se) level in barley and maize from 43 communes of Qidong county, a high risk area of liver cancer in China, were assayed. An inverse correlation between the Se level and the liver cancer incidence was observed. An inverse correlation was also observed between the blood Se level and liver cancer incidence of the local residents. When selenite solution was sprayed on the crops during their preflowering, the content of Se in barley and maize was increased by 6 fold over the control. It is suggested that the increase of blood Se level of the residents who live in the low-Se areas by this method be useful in the prevention of liver cancer.
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229
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Bragg PD, Hou C. Chemical crosslinking of alpha subunits in the F1 adenosine triphosphatase of Escherichia coli. Arch Biochem Biophys 1986; 244:361-72. [PMID: 2868692 DOI: 10.1016/0003-9861(86)90125-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The arrangement of the subunits in the F1 adenosine triphosphatase of Escherichia coli has been investigated using bifunctional chemical crosslinking agents to covalently link adjacent subunits in the enzyme molecule. The synthesis of the new cleavable crosslinking agent 2,2'-dithiobis(succinimidyl propionate) is described. The crosslinked products resulting from the reaction of the enzyme with 2,2'- and 3,3'-dithiobis(succinimidyl propionate), 3,3'-dithiobis(sulfosuccinimidyl propionate), disuccinimidyl tartrate, dimethyl adipimidate, 1-ethyl-3[3-(dimethylamino)propyl]carbodiimide, and 1,2:3,4-diepoxybutane were analyzed by "three-dimensional" polyacrylamide gel electrophoresis in which they were resolved first in a two-dimensional system. Following cleavage of the crosslinking bridge in the separated products, the constituent subunits were identified by a further one-dimensional gel electrophoresis step. This procedure greatly improved the precision with which crosslinked subunits could be identified. It largely overcame problems due to abnormal migration of crosslinked species on gel electrophoresis and to the formation of multiple species of the same crosslinked subunit dimers. The following crosslinked subunit dimers were identified: alpha alpha, alpha beta, beta gamma, alpha delta, beta epsilon, and gamma epsilon. The trimer alpha alpha delta was recognized. The formation of alpha alpha over alpha beta dimers was favored when more polar crosslinking agents were used. The constraints placed by the finding of adjacent alpha subunits upon current models for the arrangement of the subunits in the F1 ATPase are discussed.
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230
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Wang GX, Hou C. [Effect of electroacupuncture of the "zusanli" point on the exocrine secretion of the pancreas in rats]. ZHONG XI YI JIE HE ZA ZHI = CHINESE JOURNAL OF MODERN DEVELOPMENTS IN TRADITIONAL MEDICINE 1985; 5:489-92, 453. [PMID: 2932255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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231
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Yu SY, Chu YJ, Gong XL, Hou C, Li WG, Gong HM, Xie JR. Regional variation of cancer mortality incidence and its relation to selenium levels in China. Biol Trace Elem Res 1985; 7:21-9. [PMID: 24258872 DOI: 10.1007/bf02916544] [Citation(s) in RCA: 74] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/1984] [Accepted: 08/27/1984] [Indexed: 11/28/2022]
Abstract
The epidemiological relationship between selenium level and age-adjusted human cancer mortality (incidence) was studied in 24 regions located in eight provinces of China. Statistically significant inverse correlation was found between age-adjusted total cancer death rates and selenium levels in whole blood from local residents. In the areas with high selenium levels, there was significantly lower mortality in both males and females from cancer of the stomach and esophagus. In addition, an inverse correlation between regional distribution of liver cancer incidence and selenium contents in blood and grains in Qidong county, an area with high risk of hepatoma, was observed. With the intention of providing selenium supplements to residents living in low selenium regions, the selenium content in grains was raised by means of foliar spraying of crops with Na2SeO3 solution.
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232
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Chu YJ, Liu QY, Hou C, Yu SY. Blood selenium concentration in residents of areas in China having a high incidence of lung cancer. Biol Trace Elem Res 1984; 6:133-7. [PMID: 24263853 DOI: 10.1007/bf02916930] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/1983] [Accepted: 09/30/1983] [Indexed: 11/26/2022]
Abstract
Data concerning the blood selenium level and its relation to the mortality from lung cancer are reported. There were 353 samples of blood collected from workers at the Yannan Tin Mine (Yun-Xi) and 75 samples from Beijing residents for comparison. An inverse correlation between blood selenium levels and lung cancer mortalities was observed. The average selenium concentration in whole blood from Beijing residents (age-adjusted mortality rate from lung cancer for males: 12/100,000) and Yun-Xi miners (age-adjusted mortalty from lung cancer for males: 108/100,000) were 12.3 and 8.8 μg/100 mL, respectively. A similar inverse correlation was also observed among young people of comparable sex and age groups. In Yun-Xi, the tin miners working underground with an average lung cancer death rate of 250/100, 000 for males had lower blood selenium concentrations than those working above ground, where the average lung cancer death rate for males was 42/100,000. Workers frequently exposed to arsenic exhibited lower blood selenium contents. Selenium levels in the blood of patients with lung cancer were lower (6.2 μg/100 mL) than those of healthy controls.
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233
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Bragg PD, Stan-Lotter H, Hou C. Adenine nucleotide binding sites in normal and mutant adenosine triphosphatases of Escherichia coli. Arch Biochem Biophys 1982; 213:669-79. [PMID: 6462112 DOI: 10.1016/0003-9861(82)90597-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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234
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Hou C. [On the integration of traditional Chinese medicine and western medicine, modernization of traditional Chinese medicine and the creation of a new unified medicine in the world]. ZHONG XI YI JIE HE ZA ZHI = CHINESE JOURNAL OF MODERN DEVELOPMENTS IN TRADITIONAL MEDICINE 1982; 2:6-8. [PMID: 6219808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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235
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Bragg PD, Stan-Lotter H, Hou C. Affinity labeling of purified Ca2+,Mg2+-activated ATPase of Escherichia coli by the 2',3'-dialdehydes of adenosine 5'-di- and triphosphates. Arch Biochem Biophys 1981; 207:290-9. [PMID: 6454392 DOI: 10.1016/0003-9861(81)90036-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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236
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Bragg PD, Hou C. A difference in the affinity labeling of Ca2+, Mg2+-activated ATPases of normal and unc A strains of Escherichia coli by the 2',3'-dialdehyde derivative of adenosine 5'-diphosphate. Biochem Biophys Res Commun 1980; 95:952-7. [PMID: 6106481 DOI: 10.1016/0006-291x(80)91565-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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237
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Bragg PD, Hou C. A cross-linking study of the Ca2+, Mg2+-activated adenosine triphosphatase of Escherichia coli. EUROPEAN JOURNAL OF BIOCHEMISTRY 1980; 106:495-503. [PMID: 6995107 DOI: 10.1111/j.1432-1033.1980.tb04596.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The solubilized Ca2+,Mg2+-activated adenosine triphosphatase of Escherichia coli is composed of five subunits designated alpha, beta, gamma, delta and epsilon in order of decreasing molecular weight. The subunit structure of the enzyme has been investigated by the use of the cleavable cross-linking agents dithiobis(succinimidyl propionate), methyl-4-mercaptobutyrimidate, dimethyl-3,3'-dithiobispropionimidate, disuccinimidyl tartarate, and cupric 1,10-phenanthrolinate. The products of cross-linking were analyzed by two different two-dimensional gel electrophoresis systems. The following cross-linked subunit dimers were observed: alpha 2, beta 2, alpha beta, alpha delta, beta gamma, beta delta, beta epsilon and gamma epsilon. These results, together with other published data, are discussed in relation to a model of the arrangement of the subunits in the ATPase molecule.
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238
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Bragg PD, Hou C. Proteolysis of the delta subunit is required for release of the Ca2+, Mg2+-activated ATPase from the cell membrane of Escherichia coli. FEBS Lett 1979; 103:12-6. [PMID: 157286 DOI: 10.1016/0014-5793(79)81240-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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239
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Bragg PD, Hou C. Binding of the Ca2+,Mg2+-activated adenosine triphosphatase of Escherichia coli to phospholipid vesicles. CANADIAN JOURNAL OF BIOCHEMISTRY 1978; 56:559-64. [PMID: 149587 DOI: 10.1139/o78-085] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Incubation of the Ca2+,Mg2+-activated adenosine triphosphatase of Escherichia coli with phospholipid vesicles resulted in binding of the enzyme to the lipid. Binding was observed with vesicles of soybean phospholipid (asolectin), phosphatidyglycerol, phosphatidylserine, phosphatidylcholine, and cardiolpin. Binding was not affected by alterations in pH in the range of pH 6.5 to 8.5, by ionic strength, or by the presence of Mg2+. Loss of the delta subunit from the enzyme had no effect on binding. However, removal of the delta and epsilon subunits by treatment of the enzyme with trypsin prevented binding to phospholipid. This treatment also removed a small portion (less than 2000 daltons) of the alpha subunit. It is concluded that the ATPase of E. coli binds to phospholipid vesicles mainly by nonpolar interactions through the alpha and (or) epilson subunits of the enzyme.
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240
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Bragg PD, Hou C. Cross-linking of minor subunits in the adenosine triphosphatase of rat liver mitochondria. CANADIAN JOURNAL OF BIOCHEMISTRY 1977; 55:1121-4. [PMID: 144017 DOI: 10.1139/o77-167] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The subunits of the purified ATPase of rat liver mitochondria were cross-linked with the cleavable disulfide crosslinking reagent dithiobis(succinimidyl propionate). Besides cross-linking of the major (alpha,beta) subunits interactions between beta and gamma and between gamma and epsilon subunits were observed.
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241
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Wu HC, Hou C, Lin JJ, Yem DW. Biochemical characterization of a mutant lipoprotein of Escherichia coli. Proc Natl Acad Sci U S A 1977; 74:1388-92. [PMID: 323849 PMCID: PMC430769 DOI: 10.1073/pnas.74.4.1388] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
A lipoprotein mutant of E. coli K-12 has been characterized. The mutant lipoprotein was found to differ from the wild-type lipoprotein in the following respects: (i) it is present in an appreciable amount in the soluble fraction (275,000 X g supernatant); (ii) it lacks the covalently-linked diglyceride; (iii) it contains an unmodified cysteine which can be carboxymethylated in vitro; (iv) it undergoes dimerization and the dimer can be converted into monomeric form by reduction with 2-mercaptoethanol; (v) both the monomeric form and especially the dimeric form of the mutant lipoprotein migrate more slowly than the corresponding forms of wild-type lipoprotein in sodium dodecyl sulfate/urea polyacrylamide gel electrophoresis; and (vi) the mutant lipoprotein is not assembled into the murein sacculi, and this results in a greatly reduced amount of bound-form lipoprotein in the mutant. These data strongly suggest that the mutation has affected the primary structure of lipoprotein, in such a way that it is not modified normally, leading to the production of a structurally-altered lipoprotein deficient in covalently-linked lipid as well as a defective assembly of the altered lipoprotein into the rigid layer of the cell envelope.
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242
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Bragg PD, Hou C. Purification and characterization of the inactive Ca2+, Mg2+-activated adenosine triphosphatase of the unc A- mutant Escherichia coli AN120. Arch Biochem Biophys 1977; 178:486-94. [PMID: 13731 DOI: 10.1016/0003-9861(77)90219-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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243
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Bragg PD, Hou C. Cross-linking of minor subunits in Ca2+, Mg2+-activated ATPase of Escherichia coli. Biochem Biophys Res Commun 1976; 72:1042-8. [PMID: 136256 DOI: 10.1016/s0006-291x(76)80237-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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244
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Bragg PD, Hou C. Solubilization of a phospholipid-stimulated adenosine triphosphatase complex from membranes of Escherichia coli. Arch Biochem Biophys 1976; 174:553-61. [PMID: 132897 DOI: 10.1016/0003-9861(76)90383-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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245
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Bragg PD, Hou C. Subunit composition, function, and spatial arrangement in the Ca2+-and Mg2+-activated adenosine triphosphatases of Escherichia coli and Salmonella typhimurium. Arch Biochem Biophys 1975; 167:311-21. [PMID: 124154 DOI: 10.1016/0003-9861(75)90467-1] [Citation(s) in RCA: 201] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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246
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Bragg PD, Hou C. Energization of energy-dependent transhydrogenase of Escherichia coli at a second site of energy conservation. Arch Biochem Biophys 1974; 163:614-6. [PMID: 4153348 DOI: 10.1016/0003-9861(74)90521-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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247
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Bragg PD, Hou C. Reconstitution of energy-dependent transhydrogenase in ATPase-negative mutants of Escherichia coli. Biochem Biophys Res Commun 1973; 50:729-36. [PMID: 4265977 DOI: 10.1016/0006-291x(73)91305-3] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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248
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Bragg PD, Hou C. Purification of a factor for both aerobic-driven and ATP-driven energy-dependent transhydrogenases of Escherichia coli. FEBS Lett 1972; 28:309-312. [PMID: 11946884 DOI: 10.1016/0014-5793(72)80738-5] [Citation(s) in RCA: 81] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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249
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Grenson M, Hou C. Ammonia inhibition of the general amino acid permease and its suppression in NADPH-specific glutamate dehydrogenaseless mutants of saccharomyces cerevisiae. Biochem Biophys Res Commun 1972; 48:749-56. [PMID: 4404622 DOI: 10.1016/0006-291x(72)90670-5] [Citation(s) in RCA: 88] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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250
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Bragg PD, Hou C. Organization of proteins in the native and reformed outer membrane of Escherichia coli. BIOCHIMICA ET BIOPHYSICA ACTA 1972; 274:478-88. [PMID: 4558851 DOI: 10.1016/0005-2736(72)90193-9] [Citation(s) in RCA: 96] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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