NEAR ULTRAVIOLET INACTIVATION STUDIES ON<i>ESCHERICHIA COLI TRYPTOPHANASE</i> AND TRYPTOPHAN SYNTHETASE

Coetzee, W. F.; Pollard, Ernest C.

doi:10.1111/j.1751-1097.1975.tb06716.x

Cited by 14 publications

(6 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However slight damage to the nucleus is also indicated. This is consistent with the observations that near-UV light inactivates several enzymes (Roth and Hug, 1972;Tyrrell et al, 1973;Coetzee and Pollard, 1975). It has also been shown that the target for growth delay induced by near-UV light in E. coli is not DNA (Rambhadran and Jagger, 1974;Thomas and Favre, 1975).…”

Section: Discussionsupporting

confidence: 85%

Synergistic Interaction Between the Tryptophan Photoproducts and Near‐ultraviolet Light in Amoeba

Bhattacharjee

Chatterjee

1977

Photochem & Photobiology

View full text Add to dashboard Cite

Abstract. Both S‐ and G2‐phase cells of amoeba are found to be sensitized by coirradiation of cells with Tryptophan (Trp). At a fluence of 1.5 times 105 Jm‐2 to which G2 phase cells are resistant, they show a drastic (8‐fold) increase in sensitivity when irradiated in 0.5% Trp solution. Freshly irradiated Trp solution is found to be lethal to G2 cells that have received a sublethal fluence of near‐UV light. Irradiated Trp, however, does not kill unirradiated amoeba. Nuclear transplantation experiments have shown that the lethality of cells when coirradiated with Trp is due to damage located predominantly in the cytoplasm. It is suggested that sublethal fluence of near‐UV light makes the cells “leaky” to the toxic photooxidation products of Trp solution.

show abstract

Section: Discussionsupporting

confidence: 85%

Synergistic Interaction Between the Tryptophan Photoproducts and Near‐ultraviolet Light in Amoeba

Bhattacharjee

Chatterjee

1977

Photochem & Photobiology

View full text Add to dashboard Cite

show abstract

“…The action spectrum (Fig. 7) which we determined (peak, 280 nm; shoulder, 300-340 nm; minimum, 250 nm) did not correspond to the absorption of free uro-canate, pH 7.4 (peak, 277 nm; no shoulder from 300 to 340 nm; minimum, 235 nm; Tabor, 1955) or pyridoxal phosphate (peak, 388 nm, Coetzee and Pollard, 1975). Flavins and carotenoids, which are considered possible photoreceptor pigments (Song and Moore, 1974), absorb in the visible range which was not effective in this photoinactivation.…”

Section: Discussionmentioning

confidence: 68%

“…The main peak of the action spectrum (280 nm) corresponds very well with both protein, -280 nm, and urocanate (277 nm). Coetzee and Pollard (1975) found their action spectrum for near-UV inactivation of tryptophanase did not correspond to the absorption spectrum of the coenzyme, pyridoxal phosphate, which was the photosensitizer, or to the holotryptophanase.…”

Section: Discussionmentioning

confidence: 94%

The Substrate‐dependent Photoinactivation of Urocanase From Rat Liver

Hug¹,

Hunter²,

O'Donnell³

1977

Photochem & Photobiology

View full text Add to dashboard Cite

Abstract— Rat liver urocanase was readily inactivated by near‐UV light in the presence of the substrate. Irradiation of substrate or enzyme alone was ineffective. The purpose of this study was to examine the conditions which influenced this inactivation and to investigate the mechanism. The urocanate concentration needed for 50% of the maximum inactivation for a 15 min irradiation was 0.09 μM. Temperatures from 0 to 30°C during irradiation had little influence. Inactivation occurred at ‐75°C, which indicated a photochemical reaction. The pH had little influence on inactivation. Photoinactivation was the same in nitrogen and air. Dialysis experiments showed that unbound small molecules were probably not involved. Inactivated enzyme did not inhibit active enzyme. Chelators, reducing agents, and pyridoxal phosphate did not affect the inactivation. Visible light was not effective. An action spectrum was established with the aid of a monochromator. The action spectrum had a peak at 280 nm and a shoulder extending from 300 to 340 nm which rules out flavins. pyridoxal phosphate, a simple protein, and free urocanate as the chromophore. The results suggest that this photochemical process is not photodynamic action. It appears that only substrate and enzyme are needed for this photoinactivation. The enzyme‐substrate complex may be the chromophore.

show abstract

“…Coetzee and Pollard [9] have shown that E . coli trytophanase is inactivated both in uiuo and in d t w by near UV, but tryptophan synthetase is resistant to near UV under both conditions, showing that near-UV inactivation is not a general phenomenon for pyridoxal-phosphate-requiring enzymes; interestingly, the absorption spectra and action spectra are rather different, the latter being confined to the near-UV region.…”

Section: Direct Effects On Biomoleculesmentioning

confidence: 97%

Effects of Near‐ultraviolet Radiation on Microorganisms

Jagger

1976

Photochem & Photobiology

View full text Add to dashboard Cite

NEAR ULTRAVIOLET INACTIVATION STUDIES ONESCHERICHIA COLI TRYPTOPHANASE AND TRYPTOPHAN SYNTHETASE

Cited by 14 publications

References 22 publications

Synergistic Interaction Between the Tryptophan Photoproducts and Near‐ultraviolet Light in Amoeba

Synergistic Interaction Between the Tryptophan Photoproducts and Near‐ultraviolet Light in Amoeba

The Substrate‐dependent Photoinactivation of Urocanase From Rat Liver

Effects of Near‐ultraviolet Radiation on Microorganisms

Contact Info

Product

Resources

About