The Formol Titration of Bacteriological Media

Brown, J. Howard

doi:10.1128/jb.8.3.245-267.1923

Cited by 21 publications

(5 citation statements)

References 10 publications

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“…These were incubated at 3500. in an atmosphere of hydrogen; and one tube was analyzed on the second, fourth, sixth, tenth, and twentieth day respectively. After the determination of the conductivity, the sample was used for the determination of ammonia (Folin), amino nitrogen (both Van Slyke and Sorensen (Brown, 1923) and electrometric pH.…”

Section: / Imentioning

confidence: 99%

The Possibilities of the Conductivity Method as Applied to Studies of Bacterial Metabolism

Parsons¹,

Sturges²

1926

J Bacteriol

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Section: / Imentioning

confidence: 99%

The Possibilities of the Conductivity Method as Applied to Studies of Bacterial Metabolism

Parsons¹,

Sturges²

1926

J Bacteriol

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“…Being careful to avoid stirring up the meat, 1 cc. of the clear supernatant fluid was removed from each tube and formol titrations made by Brown's modification (14) of S6rensen's method. This modification is particularly adapted for use with bacteriological media.…”

Section: Nature Of the Enzymementioning

confidence: 99%

Tissue-Digesting Enzyme (Histase) of Streptococci

Frobisher

1926

Journal of Experimental Medicine

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1. An extracellular, proteolytic enzyme has been observed in more than 30 strains of beta type, aerobic and facultative hemolytic streptococci. 2. The enzyme is readily demonstrable in sterile filtrates of cooked meat cultures. 3. No gas or foul odor is produced. 4. It is partially inactivated by exposure to about 60°C. for 45 minutes or longer. 5. The enzyme manifests itself in cooked meat cultures after about 48 hours incubation at 37°C. The sterile filtrate from a 10 day old culture acts within 18 hours. 6. From 50 to 75 per cent of the meat in a tube of cooked meat medium may be digested in about 3 weeks at room temperature after 5 days initial growth at 37°C. 7. No correlation is found, in the cases studied, between hemolysis and proteolysis. 8. Streptococci not digesting beef tissue will not digest human tissue, and those which do digest beef tissue also digest human tissue. This conclusion applies only to the nine strains studied. 9. Ability to digest animal tissues does not necessarily imply ability to digest casein, coagulated beef serum or gelatin. 10. The disappearance of the meat from cooked meat cultures of hemolytic streptococci is quantitatively roughly paralleled by increase of formol-titrable substances in the fluid portion of the medium. 11. The enzyme resembles trypsin in its action. Streptococci from a variety of sources, bovine, human and otherwise have shown varying degrees of proteolytic activity. 12. The name histase is proposed for this enzyme.

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“…Following pioneering work in the 1920s, numerous studies have been reported on reactions of HCHO with amino acids (AAs) and peptides [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] . However, few detailed systematic studies have been reported on reactions of HCHO with amino acids.…”

mentioning

confidence: 99%

How formaldehyde reacts with amino acids

et al. 2019

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Formaldehyde is a biological electrophile produced via processes including enzymatic demethylation. Despite its apparent simplicity, the reactions of formaldehyde with even basic biological components are incompletely defined. Here we report NMR-based studies on the reactions of formaldehyde with common proteinogenic and other nucleophilic amino acids. The results reveal formaldehyde reacts at different rates, forming hydroxymethylated, cyclised, cross-linked, or disproportionated products of varying stabilities. Of the tested common amino acids, cysteine reacts most efficiently, forming a stable thiazolidine. The reaction with lysine is less efficient; low levels of an Nε-methylated product are observed, raising the possibility of non-enzymatic lysine methylation by formaldehyde. Reactions with formaldehyde are faster than reactions with other tested biological carbonyl compounds, and the adducts are also more stable. The results reveal reactions of formaldehyde with amino acids, and by extension peptides and proteins, have potential roles in healthy and diseased biology, as well as in evolution.

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The Formol Titration of Bacteriological Media

Cited by 21 publications

References 10 publications

The Possibilities of the Conductivity Method as Applied to Studies of Bacterial Metabolism

The Possibilities of the Conductivity Method as Applied to Studies of Bacterial Metabolism

Tissue-Digesting Enzyme (Histase) of Streptococci

How formaldehyde reacts with amino acids

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