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The fractionation of the non‐protein nitrogen of grassland herbage
Author(s) -
Ferguson W. S.,
Terry R. A.
Publication year - 1954
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740051103
Subject(s) - chemistry , fractionation , nitrogen , amino acid , ammonia , hydrolysis , nitrate , chromatography , elution , organic chemistry , biochemistry
The total non‐protein nitrogenous (NPN) fraction of oven‐dried grassland herbage has been examined. The NPN was obtained by extraction of dried herbage with boiling water and it was fractionated as follows : (1) precipitation of part of the peptide‐nitrogen with 75% alcohol, followed by (2) precipitation of purines with silver sulphate (this treatment also precipitated some peptides), followed by (3) passage through a cation‐exchange resin, which gave three main fractions : ( a ) non‐adsorbed nitrogen compounds, including nitrate, pyrimidines and unidentified substances, ( b ) adsorbed compounds which were eluted with sodium hydroxide—amino‐acids, amides, ammonia, betaines, peptides or ‘bound’amino‐acids, and unidentified substances and ( c ) basic compounds, including choline, and strongly adsorbed compounds that could not be eluted from the column with strong acid, probably mainly peptides and possibly including nucleotides. Two grasses, a clover and a lucerne sample were used and the proportion of their total nitrogen present as NPN varied from 23 to 30%. An analysis including amino‐nitrogen after hydrolysis, amide‐nitrogen, ammonia‐nitrogen, nitrate‐nitrogen, purine‐nitrogen, betaine‐nitrogen and choline‐nitrogen accounted for 77‐88% of the NPN. The fractionation gave higher recoveries when assumptions were made on the probable peptide content and it indicated where unidentified substances might be found.