NISCAIR Online Periodicals Repository Collection: IJBB Vol.36(3) [June 1999]

Biochemical and dynamic studies of collagen from human normal skin and keloid tissue

Sat, 29 May 1999 22:58:59 GMT

Title: Biochemical and dynamic studies of collagen from human normal skin and keloid tissue

Authors: Prathiba, V; Suryanarayanan, M

Abstract: Keloids are exuberant scars, in which collagen, fibronectin and glycosaminoglycans are overdeposited. Biochemical analysis of the collagen isolated from normal skin and keloid tissue by pepsin treatment, indicated an increase in the type III and GAG content. Viscosity measurements of collagen from normal skin and keloid tissue were used in the' present study to establish the interaction between collagen and GAG. Physico-chemical properties such as intrinsic viscosity, reduced viscosity and hydrated volume were computed from viscosity measurements. These measurements were also used to determine the denaturation temperature of collagen which was further confirmed by DSC measurements. Chondroitinase has been used in this study to probe the influence of GAG on the physico-chemical characteristic of keloid collagen.

Page(s): 158-164

Effect of sulphur crosslinking on the stability and transition of triple helical DNA

Sat, 29 May 1999 22:58:59 GMT

Title: Effect of sulphur crosslinking on the stability and transition of triple helical DNA

Authors: Srivastava, Seema; Gupta, Vishwambhar Dayal; Singh, Shyam

Abstract: In continuation to our work on order-order and order-disorder transition in triple stranded DNA when it is bounded to netropsin, we report in this communication the stabilizing / destabilizing effect of disulphide linkage on the phase dynamics of the triplex using the amended Zimm-Bragg theory. It is observed that in contrast to the sequential triplex → duplex → single strand melting of the uncrosslinked triplex, crosslinking causes the triplex state to melt directly to the single stranded state, with no apparent intermediary of a duplex state. Since there is no overall difference in the enthalpy of crosslinked and uncrosslinked triplexes, the transition is entropy driven.

Page(s): 177-187

Effect of water stress on proline content and transcript levels in Lathyrus sativus

Sat, 29 May 1999 22:58:59 GMT

Title: Effect of water stress on proline content and transcript levels in Lathyrus sativus

Authors: Tyagi, Aruna; Santha, I M; Mehta, S L

Abstract: Response of Lathyrus sativus plants to water stress showed that ABA responsive genes such as PLE 25, TAS 14 and RAB 17 are synthesized constitutively, the levels of which decline gradually with increase in water stress or ABA levels. Proline accumulation was highest in leaves (65-fold) followed by stern (56-fold), root (38-fold) and marginal increase in etiolated seedlings. Proline increase was also observed in plant parts not exposed to light.

Page(s): 207-210

Purification and characterization of flavokinase from Neurospora crassa

Sat, 29 May 1999 22:58:59 GMT

Title: Purification and characterization of flavokinase from Neurospora crassa

Authors: Rajeswari, Sivalenka Raja; Jonnalagadda, Vidya S; Jonnalagadda, Sobhanaditya

Abstract: The ATP-dependent phosphorylation of riboflavin to FMN by flavokinase is the key step in flavin biosynthesis. Flavokinase has been purified from a fungal source for the first time. The enzyme purified from a cell wall lacking mutant of Neurospora crassa, slime, is a monomer of M_r 35.5 kDa with maximal activity at alkaline pH and high temperature (55^°C). The K_m for both substrates is the lowest reported for flavokinase from any source so far (120 nM for riboflavin and 210 nM for MgATp^2.). The enzyme exhibits preference for Mg²⁺ over Zn²⁺ as the essential activator and is also significantly activated by several cations. Activation by orthophosphate may be physiologically relevant for the intracellular regulation of flavokinase.

Page(s): 137-142