PNL Volume 17 1985 RESEARCH REPORTS
COULOMETRIC ESTIMATION OF SULFUR AS A SCREENING METHOD FOR ESTABLISHING
TOTAL SULFUR CONTAINING AMINO ACIDS (CYSTINE AND METHIONINE) IN PEA
SEEDS
Kurasz, I., M. Stencel, and B. Wolko
Plant Experiment Station, Wiatrowo, Poland
Seeds of 17 lines from the Wiatrowo pea collection were used to
make the following determinations:
1. Percent protein content (Keil-Foss analyzer).
2. Cystine and methionine content expressed in percent of protein
(Beckman, Multichrom B amino acid analyzer).
3. Sulfur content expressed in percent of seed flour (by Dohrmann
sulfur analyzer). This was the first time that the apparatus was
used for analyzing plant materials (according to information
furnished by "Techmation", Schiphol, Amsterdam, Holland).
Amounts of sulfur-containing amino acids (percent of protein) were
measured in pea seed flour. From these values the total sulfur content
in the flour was calculated. This value was then compared with the
estimate of sulfur obtained by the Dohrmann analyzer. The Dohrmann
apparatus estimates reduced sulfur; it does not estimate sulfates. The
reduced sulfur in pea represents almost exclusively sulfur amino acids
as is evidenced by the data given in Table 1.
Conclusions:
1. The Dohrmann analyzer can be used to estimate total sulfur
amino acids in pea seeds.
2. Total sulfur amino acid content varied from line to line but
the ratio between the two sulfur-containing amino acids remained rela-
tively constant.
3. The time required to make a single sulfur determination (5 min)
is twelve times less than the time to determine cystine and methionine
by the amino acid analyzer and the cost twenty times lower. Conse-
quently, a large number of individuals can be screened, an important
advantage from the point of view of breeding and selection.
4. The sulfur amino acids can be estimated indirectly by measuring
reduced sulfur by the Dohrmann method.
A complete description of the method and results will soon be pub-
lished in "Hodowla Roslin".
This short report is dedicated to Prof. Dr. W. Gottschalk (Institut fur
Genetik der Universitat Bonn) as an acknowledgement for his cooperation
in permitting us to visit and study in his laboratory at Bonn Univer-
sity.