Biomedical subjects

N V Ignatov

Publications and source records attributed to N V Ignatov.

5 recordsLinked to original sources

PubMed2002

Biosynthesis of chlorophyll from protochlorophyll(ide) in green plant leaves.

Using spectral methods, the biosynthesis of protochlorophyll(ide) and chlorophyll(ide) in green plant leaves was studied. The main chlorophyll precursors in the green leaves (as in etiolated leaves) were photoactive photocholorophyll(ide) forms Pchl(ide)655/650(448) and Pchl(ide)653/648(440). The contributions into Chl biosynthesis of the shorter-wavelength precursor forms, which were accumulated in darkened green leaves as well, were completely absent (of Pchl(ide) 633/628(440)) or insignificant (of Pchl(ide) 642/635(444)).

Chlorophyll↗

PubMed2001

Biosynthesis of chlorophyll of photosystem II reaction centers in plant leaves in early stages of etiolation.

Spectral methods were used to study the sequences of chlorophyll biosynthesis reactions in etiolated pea, bean, and maize plants in early stages (3-4 days) of growth. For these juvenile plants, along with the reaction chain known for mature (7-9 day-old) plants, a new reaction chain was found which started with phototransformation of the long-wavelength form PChld 686/676 into PChld 653/648. (PChld 653/648 differs from the main known precursor form PChld 655/650). The subsequent photoreduction of PChld 653/648 leads to the formation of Chld 684/676, which is transformed into Chl 688/680 in the course of a dark reaction. After completion of this reaction, fast (20-30 sec) quenching of the fluorescence of the reaction product is observed with the formation of non-fluorescent Chl 680. The reaction accompanied by pigment fluorescence quenching is absent in pea mutants with depressed function of Photosystem II reaction centers. This suggests that the newly found reaction chain leads to the formation of chlorophyll of the Photosystem II reaction center.

Chlorophyll↗

PubMed1998

The final stage of chlorophyll biosynthesis and formation of reaction centres of photosystems.

The survey reviews Russian studies of the final stage of chlorophyll biosynthesis and the role of A. A. Krasnovsky (Sr.) in the development of this direction. The current state of the problem is considered. The results of studies carried out by Krasnovsky's followers at Moscow State University are summarized. Schemes of the pathways of chlorophyll and pheophytin biosynthesis, biogenesis of pigment complexes of the two photosystems of photosynthesis proposed by those scientists are presented.

Chlorophyll↗

PubMedDate not supplied

[Energy migration in photoactive complexes of chlorophyll precursor in etiolated leaves and spectroscopic characteristics of pigment forms].

Migration energy between three forms of the precursor of chlorophyll and chlorophyllide are measured and calculated. Absorption coefficients, fluorescence yields of pigment forms and dimensions of native complexes (20-22 molecules) are calculated.

Chlorophyll↗

PubMedDate not supplied

[Energy migration in a pigmented protochlorophyllide complex].

Data are analysed concerning energy migration between protochlorophyllide and chlorophyllide formed in etiolated leaves. It is found that phototransformation of the precursor proceeds in the pigment complexes similar to the multicentric photosynthetic unit. The complexes comprise no more than 26 molecules of the active form of protochlorophyllide P650 and two molecules of minor forms of P628 and P639 on the average with mean intermolecular distances 3 nm.

Chlorophyll↗