Primary Structure
In 1953 Frederick Sanger determined the complete sequence of A m
a of Insulin by
studying the primary structure of p
R
t , this sequence can be determined. Actually,
each p
R
t has a unique sequence of A m
a which is determined by the genes contained
in DNA. The primary structure of a p
R
t is largely responsible for its function (Kyte
and Doolittle 1982). The A m
a composition of a p
R
t determines its physical and
chemical properties. The primary structures formed during the translation (a process
of p
R
t biosynthesis) are held together by covalent P E
pt bonds. Depending on the
nature of the free group on each terminal of the P E
pt chain, each extremely is
referred as the carboxyl terminus (C-terminus) and the amino terminus
(N-terminus). Numbering of residues always starts at the N-terminal end (–NH 2
group) from where the amino group is involved in a P E
pt bond. The primary
structure of p
R
t depends on the gene corresponding to the p
R
t through transcription
mRNA is synthesized by a particular sequence of nucleotides. The mRNA is further
read by the ribosome in a process known as translation. The sequence of p
R
t is
specific for a p
R
t which defines the function and structure of that p
R
t . For the
determination of A m
a sequence in a p
R
t , they commonly use methods like Edman
degradation or tandem mass spectrometry (Bender and Smith 1997).
Secondary Structure
It refers to the conformation of poly P E
pt chain by twisting or folding to a secondary
structure. Two types of secondary structures are mainly identified i.e., a helix, & b
sheet.
Table 23.6 Color R e
at of p
R
t
R e
at
Observations
Specific group/A m
a
Biuret R e
at
Violet or purple color
Two P E
pt linkages
Ninhydrin R e
at
Blue color
a-A m
a
Xanthoproteic R e
at
Orange color
Aromatic A m
a
Millions R e
at
Red color
Phenolic group
Hopkins-Cole
Violet ring
Indole ring
Sakaguchi
Intense red color
Guanidino group
Nitroprusside
–
Sulfhydryl groups (Cys)
Sulfur test
Black ppt
Sulfhydryl groups (Cys)
Pauly’s test
–
Imidazole ring (His)
Folin–Coicalteau’s test
–
Phenolic groups
800
O. P. Panda et al.
In 1953 Frederick Sanger determined the complete sequence of A m
a of Insulin by
studying the primary structure of p
R
t , this sequence can be determined. Actually,
each p
R
t has a unique sequence of A m
a which is determined by the genes contained
in DNA. The primary structure of a p
R
t is largely responsible for its function (Kyte
and Doolittle 1982). The A m
a composition of a p
R
t determines its physical and
chemical properties. The primary structures formed during the translation (a process
of p
R
t biosynthesis) are held together by covalent P E
pt bonds. Depending on the
nature of the free group on each terminal of the P E
pt chain, each extremely is
referred as the carboxyl terminus (C-terminus) and the amino terminus
(N-terminus). Numbering of residues always starts at the N-terminal end (–NH 2
group) from where the amino group is involved in a P E
pt bond. The primary
structure of p
R
t depends on the gene corresponding to the p
R
t through transcription
mRNA is synthesized by a particular sequence of nucleotides. The mRNA is further
read by the ribosome in a process known as translation. The sequence of p
R
t is
specific for a p
R
t which defines the function and structure of that p
R
t . For the
determination of A m
a sequence in a p
R
t , they commonly use methods like Edman
degradation or tandem mass spectrometry (Bender and Smith 1997).
Secondary Structure
It refers to the conformation of poly P E
pt chain by twisting or folding to a secondary
structure. Two types of secondary structures are mainly identified i.e., a helix, & b
sheet.
Table 23.6 Color R e
at of p
R
t
R e
at
Observations
Specific group/A m
a
Biuret R e
at
Violet or purple color
Two P E
pt linkages
Ninhydrin R e
at
Blue color
a-A m
a
Xanthoproteic R e
at
Orange color
Aromatic A m
a
Millions R e
at
Red color
Phenolic group
Hopkins-Cole
Violet ring
Indole ring
Sakaguchi
Intense red color
Guanidino group
Nitroprusside
–
Sulfhydryl groups (Cys)
Sulfur test
Black ppt
Sulfhydryl groups (Cys)
Pauly’s test
–
Imidazole ring (His)
Folin–Coicalteau’s test
–
Phenolic groups
800
O. P. Panda et al.