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.