Some Major Steps in the Understanding of the Chemistry and Biochemistry of Chl - Chlorophyll Biosynthesis and Technological Applications - page 8

1.2 Some Major Steps in the Understanding
of the Biochemistry of Porphyrin
and Chl Formation
In this historical section emphasis is placed on important scientific discoveries that
had a clear impact on the understanding of the structure and function of interme-
diates and end-products of the porphyrin and Chl biosynthetic pathways. Most of
these discoveries will be discussed in details in various chapters of this monograph.
1.2.1 Granick, 1948a
In 1948, Granick demonstrated the accumulation of divinyl (DV) protoporphyrin
IX (Proto) in Chlorella mutants inhibited in their capability to form Chl. Since the
algal cultures that accumulated Proto were inhibited in their capabilities of forming
Chl, Granick proposed that in plants, DV Proto is a precursor of monovinyl
(MV) Chl a (Granick 1948a ). In this context, the term DV refers to tetrapyrroles
that contain vinyl groups at positions 2 and 4 of the macrocycle, while the term MV
refers to tetrapyrroles containing a vinyl group at position 2 and an ethyl group at
position 4 of the macrocycle.
1.2.2 Granick, 1948b
In 1948, Granick also demonstrated the accumulation of divinyl DV
Mg-protoporphyrin IX (Mg-Proto) in X-ray Chlorella mutants inhibited in their
capability to form Chl, and proposed that in plants, DV Mg-Proto is a precursor of
MV Chl a (Granick 1948b ).
1.2.3 Koski and Smith, 1948
In 1948, Koski and Smith, purified protochlorophyllide (Pchlide a )whichthey
mistook for Pchlide a phytyl ester [ i.e. protochlorophyll (Pchl) a ]anddetermined
its spectral absorption properties (Koski and Smith 1948 ). That mistake was
facilitated by the then erroneous notion that Pchl was the main immediate
precursor of Chl.