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The Fate of L‐Tyrosine‐UL −14 C in Shoot‐Forming Tobacco Callus
Author(s) -
HASEGAWA PAUL M.,
MURASHIGE TOSHIO,
MUDD J. BRIAN
Publication year - 1977
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1977.tb05561.x
Subject(s) - centrifugation , pellet , callus , fractionation , chromatography , chemistry , tyrosine , sucrose , pronase , differential centrifugation , fraction (chemistry) , biochemistry , biology , botany , enzyme , zoology , trypsin
Tobacco callus fed L‐tyrosine‐UL −14 C was sampled at 3‐day intervals for 15 days, homogenized and studied with respect to distribution of incorporated radioactivity. The supernatant obtained by centrifuging of the homogenates at 270 g contained the bulk of the radioactivity although significant activity was also detected in the pellet. Sucrose density gradient centrifugation of the supernatant showed over 90% of the recovered label to be associated with a fraction designated as “less dense than mitochondria”, with the remainder being found in the fraction identified as “mitochondria”. During tissue culture, virtually all of the radioactivity in the fraction “less dense than mitochondria” was recovered in the supernatant obtained by centrifugation at 100,000 g. From 4 to 18% of the labeling in the 100,000 g supernatant fraction was attributable to tyrosine‐containing protein, and the rest to free tyrosine and unidentified anionic constituents. The highest proportions of radio‐activity in the 270 g pellet were associated with substances extractable with NaCl, pronase, 4.6 N NaOH, and acetolyzing reagent. Low but substantial labeling characterized the extracts obtained with Triton X‐100 and 1 N NaOH. The final unextractable residue contained 20% of the 270 g pellet radioactivity.