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421.
Amit K Singh Nisha Pandey Mau Sinha Punit Kaur Sujata Sharma Tej P Singh 《International Journal of Biochemistry and Molecular Biology》2011,2(4):328-339
Lactoperoxidase (LPO) is a member of the family of mammalian heme peroxidases. It catalyzes the oxidation of halides and pseudohalides in presence of hydrogen peroxide. LPO has been co-crystallized with inorganic substrates, SCN-, I-, Br- and Cl-. The structure determination of the complex of LPO with above four substrates showed that all of them occupied distinct positions in the substrate binding site on the distal heme side. The bound substrate ions were separated from each other by one or more water molecules. The heme iron is coordinated to His-351 Nϵ2 on the proximal side while it is coordinated to conserved water molecule W-1 on the distal heme side. W-1 is hydrogen bonded to Br- ion which is followed by Cl- ion with a hydrogen bonded water molecule W-5′ between them. Next to Cl- ion is a hydrogen bonded water molecule W-7′ which in turn is hydrogen bonded to W-8′ and N atom of SCN-. W-80 is hydrogen bonded to W-9′ which is hydrogen bonded to I-. SCN- ion also interacts directly with Asn-230 and through water molecules with Ser-235 and Phe-254. Therefore, according to the locations of four substrate anions, the order of preference for binding to lactoperoxidase is observed as Br- > Cl- > SCN- > I-. The positions of anions are further defined in terms of subsites where Br- is located in subsite 1, Cl- in subsite 2, SCN- in subsite 3 and I- in subsite 4. 相似文献
422.
Jaime A. Teixeira da Silva Nisha Singh Michio Tanaka 《Plant Cell, Tissue and Organ Culture》2006,84(2):100119-100128
Protocorm-like bodies (PLBs) and callus were induced in epiphytic hybrid Cymbidium Twilight Moon ‘Day Light’, where induction capacity was strongly explant dependent. Following the use of various explant
sources (PLB, leaf tip or base, root tip or base, cell and tissue ‘suspension’), highest PLB formation and callus induction
occurred when we used whole PLBs, PLB segments or PLB transverse thin cell layers (tTCLs) or longitudinal TCLs (lTCLs). Plantlet
growth and photosynthetic state from whole or bisected PLBs, as well as from tTCLs were not significantly different, after
analysis of chlorophyll content. However plantlets generated from lTCLs showed lower values for growth and photosynthetic
parameters. All resultant plants were shown to be cytogenetically identical using RAPD and mtDNA analysis despite cytological
variation and endopolyploidy occuring between different plant parts. Acclimatization and survival rate was shown to be 100%
in the generated plants. 相似文献
423.
Annatto (Bixa orellana L.) is an important dye-yielding medium-sized tree occurring in the tropics. Investigations aimed at elucidating the reproductive
characters as well as establishing a set of breeding parameters for genetic improvement of B. orellana was carried out. Records on pollen/ovule ratios of annatto showed that this species is xenogamous. The acetolyzed pollen
of B. orellana was tricolporate. The fluorochromatic test showed 95% pollen viability. The viability of the pollen grains decreased sharply
after 4 h from anther dehiscence. The optimum time range for artificial pollination was standardized between 12:00 and 13:00 h.
A high in vitro germination rate (92%) of freshly collected pollen was recorded in modified Brewbaker’s medium with 15% sucrose.
Resource allocation studies showed that the construction of each flower cost 1.162 g. The floral vegetative cost was 75%.
Of the total allocation, 21% was spent by the stamens. Based on identified reproductive characters, controlled pollination
experiments were conducted by selecting four morphologically distinct parent plants: (1) green-fruited with reddish spines,
(2) red-fruited, (3) brown large-fruited, and (4) with brown distorted fruits. In artificial cross-pollination experiments,
wide variation ranges in fruit set (0–95%) and fruit maturation (0–85%) were observed in different crosses. The number of
seeds per capsule also showed variation (0–40 per capsule). Germination studies of seeds raised from different crosses showed
a maximum 93% germination. The present study proved that improvement in B. orellana could be achieved by adopting breeding techniques using specifically selected parents. 相似文献
424.
425.
Veena Jain Nisha Garg H. S. Nainawatee 《World journal of microbiology & biotechnology》1990,6(4):434-436
Rhizobium meliloti-alfalfa (Medicago sativa) symbiosis was influenced by the rhizospheric application of naringenin which increased nodule number, nodule weight (2-to 8-fold) and nitrogenase activity. Plant blomass and total nitrogen content also increased by 60 to 72%. The enhancing effects of naringenin were more pronounced if it was applied at the early vegetative stage of plant growth or at the time of sowing. 相似文献