Linked Life Data

10228581

Source:http://linkedlifedata.com/resource/pubmed/id/10228581

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1999-6-14
pubmed:abstractText
The photoinduced electrical events at energy-conserving chloroplast membranes can be studied in whole plastids using suction electrodes. In chloroplasts of Peperomia metallica the kinetic profile of photocurrent contains a minor outward component that occurs prior to and differs in polarity from the main component. The origin of this outward current was analyzed using single-turnover flashes in combination with prolonged light exposures and differential physicochemical treatments of tip-located (internal) and the exposed parts of a chloroplast. The outward current signal was higher after 10- to 20-s preillumination and gradually reduced in darkness. The relative amplitude of the outward peak current was enhanced when photosystem II (PS II) was excited by flashes given in the presence of far-red background light (lambda = 712 nm). The outward current was small or absent under conditions promoting activity of photosystem I (cyclic electron transport supported by artificial redox mediators in the presence of diuron) and was particularly high in the presence of PS II electron acceptors (e.g., p-phenylenediamine). This indicates the predominant association of the outward current with activity of PS II. The external application of diuron strongly inhibited the inward current, giving rise to a temporal increase in the outward current. On the contrary, when diuron was added into the suction pipette, the outward current was inhibited soon after sealing. The data suggest that the outward current originated in the tip-located portions of the thylakoid membrane that have orientation opposite to the exposed part of 'whole thylakoid'. These tip-located membrane portions are least accessible for inhibitors added into the outer medium and are highly sensitive to inhibitors (diuron), ionophores (gramicidin D), and detergents (Triton X-100) added into the pipette. Differential involvement of two photosystems in generation of the outward current may be caused by uneven structural distribution of photosystems I and II between appressed (granal) and nonappressed (stromal) thylakoids and by different recording configurations for these thylakoids.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0302-4598
pubmed:author
pubmed:issnType
Print
pubmed:volume
48
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
141-8
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1999
pubmed:articleTitle
Outward photocurrent component in chloroplasts of Peperomia metallica and its assignment to the 'closed thylakoid' recording configuration.
pubmed:affiliation
Biophysics Department, Faculty of Biology, Moscow State University, Russian Federation.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't