World's Best Scientists 2026 revealed!

D-Index & Metrics

Chemistry

D-Index
61
Citations
11190
World Ranking
9406
National Ranking
2650

Biology and Biochemistry

D-Index
61
Citations
11292
World Ranking
11524
National Ranking
4972

Research.com Recognitions

  • 1968 - US President's National Medal of Science "For his profound study of the chemical activities of microorgqanisms, including the unraveling of fatty acid metabolism and the discovery of the active coenzyme form of vitamin B12.", Presented by President Johnson at a White House ceremony on January 17, 1969.
  • 1961 - Fellow of John Simon Guggenheim Memorial Foundation
  • 1953 - Fellow of the American Association for the Advancement of Science (AAAS)
  • 1953 - Member of the National Academy of Sciences
  • 1941 - Fellow of John Simon Guggenheim Memorial Foundation

Overview

What is he best known for?

The fields of study he is best known for:

  • Enzyme
  • Biochemistry
  • Organic chemistry

H. A. Barker spends much of his time researching Biochemistry, Cofactor, Clostridium kluyveri, Enzyme and Organic chemistry. As a member of one scientific family, he mostly works in the field of Biochemistry, focusing on Clostridium and, on occasion, Caproic Acid. His Cofactor research incorporates themes from Isolation, Cyanocobalamin, Stereochemistry and Benzimidazole.

His work carried out in the field of Stereochemistry brings together such families of science as Amino acid, Glutamic acid and Aspartic acid. The concepts of his Clostridium kluyveri study are interwoven with issues in Ethanol and Fatty acid synthesis. His work in the fields of Specific activity and Size-exclusion chromatography overlaps with other areas such as Lysine 2,3-aminomutase and Isonicotinic acid.

His most cited work include:

  • Isolation and properties of crystalline cobamide coenzymes containing benzimidazole or 5, 6-dimethylbenzimidazole. (249 citations)
  • Fatty acid synthesis by enzyme preparations of Clostridium kluyveri. VI. Reactions of acyl phosphates. (234 citations)
  • A COENZYME CONTAINING PSEUDOVITAMIN B12 (195 citations)

What are the main themes of his work throughout his whole career to date?

H. A. Barker mainly focuses on Biochemistry, Clostridium, Enzyme, Cofactor and Clostridium kluyveri. His research in Biochemistry intersects with topics in Methane and Cyanide. His Clostridium research focuses on subjects like Uric acid, which are linked to Bioinformatics.

His Enzyme study integrates concerns from other disciplines, such as Divalent and Sucrose. The study incorporates disciplines such as Mutase, Cyanocobalamin, Chromatography, Stereochemistry and Benzimidazole in addition to Cofactor. He combines subjects such as Ethanol, Caproic Acid, Butyrate, Fatty acid synthesis and Butyric acid with his study of Clostridium kluyveri.

He most often published in these fields:

  • Biochemistry (63.64%)
  • Clostridium (25.25%)
  • Enzyme (21.21%)

What were the highlights of his more recent work (between 1969-2006)?

  • Stereochemistry (19.19%)
  • Enzyme (21.21%)
  • Lysine (8.08%)

In recent papers he was focusing on the following fields of study:

The scientist’s investigation covers issues in Stereochemistry, Enzyme, Lysine, Metabolism and Biochemistry. His Stereochemistry research includes elements of Coenzyme B and Substrate. His Size-exclusion chromatography study in the realm of Enzyme interacts with subjects such as Coenzyme A.

His studies in Lysine integrate themes in fields like Chromatography, Elution and Ammonia. His work in Chromatography tackles topics such as Clostridium which are related to areas like Pyridoxal phosphate. His Acetyl-CoA study in the realm of Biochemistry connects with subjects such as Glutamate synthase.

Between 1969 and 2006, his most popular works were:

  • Lysine 2,3-aminomutase. Purification and properties of a pyridoxal phosphate and S-adenosylmethionine-activated enzyme. (184 citations)
  • Metabolism of L-beta-lysine by a Pseudomonas. Purification and properties of a deacetylase-thiolesterase utilizing 4-acetamidobutyryl CoA and related compounds. (38 citations)
  • GLUTAMATE MUTASE REACTION. (23 citations)

In his most recent research, the most cited papers focused on:

  • Enzyme
  • Organic chemistry
  • Biochemistry

His scientific interests lie mostly in Biochemistry, Substrate, Stereochemistry, Glutamate decarboxylase and Glutamate synthase. His Biochemistry research focuses on Acyl-CoA in particular. The study incorporates disciplines such as Mutase, Photochemistry, Hydrogen and Cofactor in addition to Substrate.

Many of his research projects under Stereochemistry are closely connected to Isomerization with Isomerization, tying the diverse disciplines of science together. His study in Glutamate decarboxylase is interdisciplinary in nature, drawing from both Amino acid, Glycine, Isomerase, Cysteine and Metabolism.

Best Publications

  • Isolation and properties of crystalline cobamide coenzymes containing benzimidazole or 5, 6-dimethylbenzimidazole.

    H.A. Barker;R.D. Smyth;H. Weissbach;J.I. Toohey

  • A COENZYME CONTAINING PSEUDOVITAMIN B12

    H. A. Barker;H. Weissbach;R. D. Smyth

  • Fatty acid synthesis by enzyme preparations of Clostridium kluyveri. VI. Reactions of acyl phosphates.

    E. R. Stadtman;H. A. Barker

  • Two Pathways of Glutamate Fermentation by Anaerobic Bacteria

    Wolfgang Buckel;H. A. Barker

  • Lysine 2,3-aminomutase. Purification and properties of a pyridoxal phosphate and S-adenosylmethionine-activated enzyme.

    T.P. Chirpich;V. Zappia;R.N. Costilow;H.A. Barker

  • Assay, Purification, and Properties of the Adenylcobamide Coenzyme

    H.A. Barker;R.D. Smyth;H. Weissbach;Agnete Munch-Petersen

  • The purification and properties of beta-methylaspartase.

    H.A. Barker;R.D. Smyth;R. Marilyn Wilson;H. Weissbach

  • Studies with bacterial sucrose phosphorylase; the mechanism of action of sucrose phosphorylase as a glucose-transferring enzyme (transglucosidase).

    Michael Doudoroff;H.A. Barker;W.Z. Hassid

  • Biological formation of methane

    H. A. Barker;A. M. Buswell

  • The energy metabolism of Clostridium kluyveri and the synthesis of fatty acids.

    B.T. Bornstein;H.A. Barker

  • Clostridium kluyverii, an Organism Concerned in the Formation of Caproic Acid from Ethyl Alcohol

    H. A. Barker;S. M. Taha

  • STUDIES ON THE METHANE FERMENTATION X. A New Formate-Decomposing Bacterium, Methanococcus vannielii

    Thressa C. Stadtman;H. A. Barker

  • The Synthesis of Butyric and Caproic Acids from Ethanol and Acetic Acid by Clostridium Kluyveri.

    H. A. Barker;M. D. Kamen;B. T. Bornstein

  • Carbon Dioxide Utilization in the Synthesis of Acetic Acid by Clostridium Thermoaceticum.

    H. A. Barker;M. D. Kamen

  • Fatty acid synthesis by enzyme preparations of Clostridium kluyveri; preparation of cell-free extracts that catalyze the conversion of ethanol and acetate to butyrate and caproate.

    E R Stadtman;H A Barker

  • Studies on the methane fermentation. XII. The pathway of hydrogen in the acetate fermentation.

    Martin J. Pine;H. A. Barker

  • THE GLUTAMATE MUTASE SYSTEM. ASSAYS AND PROPERTIES.

    H.A. Barker;V. Rooze;F. Suzuki;A.A. Iodice

  • Clostridium acidi-uridi and Clostridium cylindrosporum, Organisms Fermenting Uric Acid and Some Other Purines.

    H. A. Barker;J. V. Beck

  • STUDIES ON THE METHANE FERMENTATION V. BIOCHEMICAL ACTIVITIES OF METHANOBACTERIUM OMELIANSKII

    H.A. Barker

  • Isolation of coenzyme B12 from liver.

    J.I. Toohey;H.A. Barker

Frequent Co-Authors

W. Z. Hassid
W. Z. Hassid University of California, Berkeley
Herbert Weissbach
Herbert Weissbach Florida Atlantic University
Martin D. Kamen
Martin D. Kamen University of California, San Diego
Jesse C. Rabinowitz
Jesse C. Rabinowitz University of California, Berkeley
Wolfgang Buckel
Wolfgang Buckel Philipp University of Marburg

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