Urea cycle enzymes in retina, ciliary body-iris, lens and senile cataracts

Rao Gadiparthi, Edward Cotlier

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Carbamylation of lens proteins induces conformational changes and may play a role in the development of cataracts in uremic patients. Thus, the activities of the urea cycle enzymes: carbamyl phosphate synthetase I, ornithine transcarbamylase, argininosuccinate synthetase, argininosuccinase and arginase, were determined in lens, retina and ciliary body-iris of calf and rabbit. No ornithine transcarbamylase activity was found in ciliary body-iris, lens and retina of calf and rabbit whereas carbamyl phosphate synthetase I, argininosuccinate synthetase, argininosuccinase and arginase activities in calf lens were 5·02±0·21, 9·50±0·29, 9·17±0·16 and 6·32±0·19 [μmol (g protein)-1 hr-1], respectively. Except arginase, the activities of carbamyl phosphate synthetase I, argininosuccinate synthetase and argininosuccinase in lens were 30-50% of the values in retina or ciliary body-iris. The Km for each of the substrates was obtained for argininosuccinate synthetase, argininosuccinase and arginase of calf lens. Activities of carbamyl phosphate synthetase I, argininosuccinate synthetase, argininosuccinase and arginase in clear human lenses, aged 67-87 years, were 0·11±0·01, 0·67±0·01, 0·20±0·01 and 0·58±0·03 (μmol lens-1 hr-1), respectively. Two-fold increase in the activity of arginase was found in senile cataracts, but all other enzymes had 36-87% decreases in activities. It is likely that the rise in arginase activity in cataracts could facilitate polyamine synthesis through ornithine and ornithine decarboxylase and additional formation of cyanate, a carbamylating compound, both of which have been implicated in cataract formation. Further, decreased activities of argininosuccinate synthetase and argininosuccinase together with increased arginase activity could lead to the depletion of arginine in senile cataracts.

Original languageEnglish (US)
Pages (from-to)483-495
Number of pages13
JournalExperimental Eye Research
Volume39
Issue number4
DOIs
StatePublished - Jan 1 1984

Fingerprint

Arginase
Ciliary Body
Argininosuccinate Lyase
Argininosuccinate Synthase
Iris
Cataract
Lenses
Urea
Retina
Carbamyl Phosphate
Enzymes
Ligases
Ornithine Carbamoyltransferase
Cyanates
Rabbits
Activity Cycles
Crystallins
Ornithine
Ornithine Decarboxylase
Polyamines

All Science Journal Classification (ASJC) codes

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

Cite this

Urea cycle enzymes in retina, ciliary body-iris, lens and senile cataracts. / Gadiparthi, Rao; Cotlier, Edward.

In: Experimental Eye Research, Vol. 39, No. 4, 01.01.1984, p. 483-495.

Research output: Contribution to journalArticle

@article{1c77d72e3c684a909b8575085505658e,
title = "Urea cycle enzymes in retina, ciliary body-iris, lens and senile cataracts",
abstract = "Carbamylation of lens proteins induces conformational changes and may play a role in the development of cataracts in uremic patients. Thus, the activities of the urea cycle enzymes: carbamyl phosphate synthetase I, ornithine transcarbamylase, argininosuccinate synthetase, argininosuccinase and arginase, were determined in lens, retina and ciliary body-iris of calf and rabbit. No ornithine transcarbamylase activity was found in ciliary body-iris, lens and retina of calf and rabbit whereas carbamyl phosphate synthetase I, argininosuccinate synthetase, argininosuccinase and arginase activities in calf lens were 5·02±0·21, 9·50±0·29, 9·17±0·16 and 6·32±0·19 [μmol (g protein)-1 hr-1], respectively. Except arginase, the activities of carbamyl phosphate synthetase I, argininosuccinate synthetase and argininosuccinase in lens were 30-50{\%} of the values in retina or ciliary body-iris. The Km for each of the substrates was obtained for argininosuccinate synthetase, argininosuccinase and arginase of calf lens. Activities of carbamyl phosphate synthetase I, argininosuccinate synthetase, argininosuccinase and arginase in clear human lenses, aged 67-87 years, were 0·11±0·01, 0·67±0·01, 0·20±0·01 and 0·58±0·03 (μmol lens-1 hr-1), respectively. Two-fold increase in the activity of arginase was found in senile cataracts, but all other enzymes had 36-87{\%} decreases in activities. It is likely that the rise in arginase activity in cataracts could facilitate polyamine synthesis through ornithine and ornithine decarboxylase and additional formation of cyanate, a carbamylating compound, both of which have been implicated in cataract formation. Further, decreased activities of argininosuccinate synthetase and argininosuccinase together with increased arginase activity could lead to the depletion of arginine in senile cataracts.",
author = "Rao Gadiparthi and Edward Cotlier",
year = "1984",
month = "1",
day = "1",
doi = "10.1016/0014-4835(84)90048-4",
language = "English (US)",
volume = "39",
pages = "483--495",
journal = "Experimental Eye Research",
issn = "0014-4835",
publisher = "Academic Press Inc.",
number = "4",

}

TY - JOUR

T1 - Urea cycle enzymes in retina, ciliary body-iris, lens and senile cataracts

AU - Gadiparthi, Rao

AU - Cotlier, Edward

PY - 1984/1/1

Y1 - 1984/1/1

N2 - Carbamylation of lens proteins induces conformational changes and may play a role in the development of cataracts in uremic patients. Thus, the activities of the urea cycle enzymes: carbamyl phosphate synthetase I, ornithine transcarbamylase, argininosuccinate synthetase, argininosuccinase and arginase, were determined in lens, retina and ciliary body-iris of calf and rabbit. No ornithine transcarbamylase activity was found in ciliary body-iris, lens and retina of calf and rabbit whereas carbamyl phosphate synthetase I, argininosuccinate synthetase, argininosuccinase and arginase activities in calf lens were 5·02±0·21, 9·50±0·29, 9·17±0·16 and 6·32±0·19 [μmol (g protein)-1 hr-1], respectively. Except arginase, the activities of carbamyl phosphate synthetase I, argininosuccinate synthetase and argininosuccinase in lens were 30-50% of the values in retina or ciliary body-iris. The Km for each of the substrates was obtained for argininosuccinate synthetase, argininosuccinase and arginase of calf lens. Activities of carbamyl phosphate synthetase I, argininosuccinate synthetase, argininosuccinase and arginase in clear human lenses, aged 67-87 years, were 0·11±0·01, 0·67±0·01, 0·20±0·01 and 0·58±0·03 (μmol lens-1 hr-1), respectively. Two-fold increase in the activity of arginase was found in senile cataracts, but all other enzymes had 36-87% decreases in activities. It is likely that the rise in arginase activity in cataracts could facilitate polyamine synthesis through ornithine and ornithine decarboxylase and additional formation of cyanate, a carbamylating compound, both of which have been implicated in cataract formation. Further, decreased activities of argininosuccinate synthetase and argininosuccinase together with increased arginase activity could lead to the depletion of arginine in senile cataracts.

AB - Carbamylation of lens proteins induces conformational changes and may play a role in the development of cataracts in uremic patients. Thus, the activities of the urea cycle enzymes: carbamyl phosphate synthetase I, ornithine transcarbamylase, argininosuccinate synthetase, argininosuccinase and arginase, were determined in lens, retina and ciliary body-iris of calf and rabbit. No ornithine transcarbamylase activity was found in ciliary body-iris, lens and retina of calf and rabbit whereas carbamyl phosphate synthetase I, argininosuccinate synthetase, argininosuccinase and arginase activities in calf lens were 5·02±0·21, 9·50±0·29, 9·17±0·16 and 6·32±0·19 [μmol (g protein)-1 hr-1], respectively. Except arginase, the activities of carbamyl phosphate synthetase I, argininosuccinate synthetase and argininosuccinase in lens were 30-50% of the values in retina or ciliary body-iris. The Km for each of the substrates was obtained for argininosuccinate synthetase, argininosuccinase and arginase of calf lens. Activities of carbamyl phosphate synthetase I, argininosuccinate synthetase, argininosuccinase and arginase in clear human lenses, aged 67-87 years, were 0·11±0·01, 0·67±0·01, 0·20±0·01 and 0·58±0·03 (μmol lens-1 hr-1), respectively. Two-fold increase in the activity of arginase was found in senile cataracts, but all other enzymes had 36-87% decreases in activities. It is likely that the rise in arginase activity in cataracts could facilitate polyamine synthesis through ornithine and ornithine decarboxylase and additional formation of cyanate, a carbamylating compound, both of which have been implicated in cataract formation. Further, decreased activities of argininosuccinate synthetase and argininosuccinase together with increased arginase activity could lead to the depletion of arginine in senile cataracts.

UR - http://www.scopus.com/inward/record.url?scp=0021748203&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0021748203&partnerID=8YFLogxK

U2 - 10.1016/0014-4835(84)90048-4

DO - 10.1016/0014-4835(84)90048-4

M3 - Article

VL - 39

SP - 483

EP - 495

JO - Experimental Eye Research

JF - Experimental Eye Research

SN - 0014-4835

IS - 4

ER -