PMID- 8549682
OWN - NLM
STAT- MEDLINE
DCOM- 19960220
LR  - 20190816
IS  - 0014-4835 (Print)
IS  - 0014-4835 (Linking)
VI  - 61
IP  - 4
DP  - 1995 Oct
TI  - Effect of cross-linking on the chaperone-like function of alpha crystallin.
PG  - 413-21
AB  - Alpha crystallin can function as a molecular chaperone in suppressing the 
      heat-induced aggregation of other crystallins and proteins. During 
      cataractogenesis, alpha-crystallin becomes a water-insoluble, 
      high-molecular-weight, cross-linked aggregate. To determine whether the chaperone 
      activity of alpha crystallin is lost during this age-related modification, 
      extracts were prepared by sonication of water-insoluble proteins isolated from 
      aged bovine lenses and human cataract lenses. All the preparations were tested 
      for chaperone-like activity using beta L-crystallin as the target protein and the 
      percentage of alpha-crystallin in water-insoluble sonicated supernatant (WISS) 
      was determined by slot blot immunoassay. The WISS from bovine as well as human 
      lenses were still effective in protecting beta L-crystallin aggregation at 56 
      degrees C. The bovine cortical WISS with 50% immunoreactive alpha-crystallin 
      showed 62% of the chaperone-like activity displayed by native alpha-crystallin. 
      The WISS from bovine lens nucleus and human lenses with 17% and 5% immunoreactive 
      alpha-crystallin showed 19% and 4% chaperone-like activity compared to native 
      alpha-crystallin. Prior treatment of the WISS of both bovine and human lenses 
      with dithiothreitol resulted in nearly 50% increase in chaperone-like activity 
      suggesting possible loss of chaperone-like activity due to disulfide cross-links. 
      To see if the chaperone-like activity of alpha-crystallin can be altered by 
      non-disulfide cross-linking, native alpha-crystallin isolated from bovine lenses 
      was cross-linked with dimethylsuberimidate (DMS) and dimethyl 
      3,3'-dithiobispropionimidate (DTBP) and tested for chaperone-like activity. The 
      DMS cross-linked alpha-crystallin was effective in inhibiting the aggregation of 
      beta L-crystallins at 56 degrees C, but required a two- to five-fold higher 
      concentration than the native alpha-crystallin. alpha-Crystallin with higher 
      degree of cross-linking showed lower chaperone-like activity. alpha-Crystallin 
      cross-linked with DTBP, a cleavable cross-linking agent, also showed a 80% loss 
      in chaperone-like activity. However, when the DTBP cross-linked alpha-crystallin 
      was treated with dithiothreitol to cleave the cross-links there was a 50% 
      recovery in the chaperone-like activity. These data suggest that the age-related 
      cross-linking, which restricts the molecular flexibility of alpha-crystallin 
      decreases its chaperone-like function.
FAU - Sharma, K K
AU  - Sharma KK
AD  - Mason Institute of Ophthalmology, University of Missouri, Columbia 65212, USA.
FAU - Ortwerth, B J
AU  - Ortwerth BJ
LA  - eng
GR  - EY 02035/EY/NEI NIH HHS/United States
GR  - EY 09855/EY/NEI NIH HHS/United States
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - England
TA  - Exp Eye Res
JT  - Experimental eye research
JID - 0370707
RN  - 0 (Cross-Linking Reagents)
RN  - 0 (Crystallins)
RN  - 0 (Imidoesters)
RN  - 29878-26-0 (Dimethyl Suberimidate)
RN  - 59012-54-3 (dimethyl dithiobispropionimidate)
SB  - IM
MH  - Aged
MH  - Aged, 80 and over
MH  - Aging
MH  - Animals
MH  - Cataract/metabolism
MH  - Cattle
MH  - Cross-Linking Reagents/pharmacology
MH  - Crystallins/*chemistry/drug effects/*physiology
MH  - Dimethyl Suberimidate/pharmacology
MH  - Hot Temperature
MH  - Humans
MH  - Imidoesters/pharmacology
MH  - Lens, Crystalline/chemistry
MH  - Protein Denaturation
MH  - *Protein Folding
MH  - *Protein Structure, Secondary
EDAT- 1995/10/01 00:00
MHDA- 1995/10/01 00:01
CRDT- 1995/10/01 00:00
PHST- 1995/10/01 00:00 [pubmed]
PHST- 1995/10/01 00:01 [medline]
PHST- 1995/10/01 00:00 [entrez]
AID - 10.1016/s0014-4835(05)80136-8 [doi]
PST - ppublish
SO  - Exp Eye Res. 1995 Oct;61(4):413-21. doi: 10.1016/s0014-4835(05)80136-8.