263
14
mechanical strength. Important examples
are keratins and collagen.
5 Globular proteins (spheroidal proteins)
have a spherical or elliptical structure.
They are water soluble and usually have
a dynamic function in the organism, e.g.
as transport proteins. An example of this
is haemoglobin, the oxygen transporting
dye of red blood cells.
5 Proteins can be denatured by external
influences or undergo chemical reactions,
such as the Maillard reaction.
? Ten Quickies
1. Differentiate between proteinogenic,
essential and non-proteinogenic amino
acids!
2. In which subgroups can the 20
proteinogenic amino acids be divided?
3. Which amino acids are represented by
the abbreviations Asn, Asp, Arg, Gln, Glu,
Ile and Trp?
4. Which substrates are required for a
Strecker synthesis? Which aldehyde
is required for the synthesis of valine?
Does this synthesis produce a single
enantiomer or a racemate?
5. What is casein? Which amino acids were
first discovered in casein?
6. What are methionine and glutamic acid
mainly used for?
7. Name the four main amino acid
extraction methods!
8. Why is the non-proteinogenic amino acid
l-Dopa important?
9. What are peptides? Distinguish between
oligopeptides, polypeptides and proteins!
10. Describe the two different structural
types of proteins!
References
Monographs and Review Articles
Skern T (2018) Exploring protein structure: principles and
practice. Springer International Publishing
Bornscheuer UT, Höhne M (eds) (2018) Protein engineering - methods and protocols. Humana Press
Kessel A, Ben-Tal N (2018) Introduction to proteins - structure, function, and motion, 2nd ed. CRC Press, Chapman & Hall
Summary (Take-Home Messages)
5 Amino acids are divided into
proteinogenic and non-proteinogenic
amino acids. 20 proteinogenic amino
acids are found in the proteins.
5 Humans must take up some amino acids
with their diet, so-called essential amino
acids, because they cannot produce them
their selves.
5 α-amino acids have the general formula
R-CH(NH 2 )COOH. Most α-amino acids
have uncharged aliphatic or aromatic
residues R. Aspartic and glutamic
acids also contain another carboxyl
group; the three amino acids lysine,
arginine and histidine contain other
nitrogen-containing groups and are
positively charged at pH 7.
5 Amino acids are produced either by
protein hydrolysis, by chemical or
enzymatic synthesis or by fermentation.
5 Non-proteinogenic amino acids include
l-thyroxine, diiodtyrosine (DIT) and
l-Dopa, a precursor of dopamine. It is
used to treat Parkinson’s disease.
5 Peptides are divided into low-molecular
weight oligopeptides and higher
molecular weight polypeptides. From a
molecular mass of approx. 12,000 Dalton,
one speaks of proteins.
5 Important peptides include the synthetic
sweetener aspartame, the hormone
insulin, which regulates blood sugar
levels, and the pharmaceutically active
penicillins and cephalosporins.
5 In the case of proteins, a distinction is
made between simple and compound
proteins, which contain additional
prosthetic groups such as carbohydrates
or lipids.
5 The molecular masses of the proteins
range from 12,000 to one million Dalton.
5 Proteins are divided into primary,
secondary, tertiary and quaternary
structures. The structure is decisive for
the biological function of the proteins.
5 Fibrillary proteins (sclerotic or fibrous
proteins) have a leaflet structure and are
important for the stability and protection
of the organism because of their
14.3 · Proteins
14
mechanical strength. Important examples
are keratins and collagen.
5 Globular proteins (spheroidal proteins)
have a spherical or elliptical structure.
They are water soluble and usually have
a dynamic function in the organism, e.g.
as transport proteins. An example of this
is haemoglobin, the oxygen transporting
dye of red blood cells.
5 Proteins can be denatured by external
influences or undergo chemical reactions,
such as the Maillard reaction.
? Ten Quickies
1. Differentiate between proteinogenic,
essential and non-proteinogenic amino
acids!
2. In which subgroups can the 20
proteinogenic amino acids be divided?
3. Which amino acids are represented by
the abbreviations Asn, Asp, Arg, Gln, Glu,
Ile and Trp?
4. Which substrates are required for a
Strecker synthesis? Which aldehyde
is required for the synthesis of valine?
Does this synthesis produce a single
enantiomer or a racemate?
5. What is casein? Which amino acids were
first discovered in casein?
6. What are methionine and glutamic acid
mainly used for?
7. Name the four main amino acid
extraction methods!
8. Why is the non-proteinogenic amino acid
l-Dopa important?
9. What are peptides? Distinguish between
oligopeptides, polypeptides and proteins!
10. Describe the two different structural
types of proteins!
References
Monographs and Review Articles
Skern T (2018) Exploring protein structure: principles and
practice. Springer International Publishing
Bornscheuer UT, Höhne M (eds) (2018) Protein engineering - methods and protocols. Humana Press
Kessel A, Ben-Tal N (2018) Introduction to proteins - structure, function, and motion, 2nd ed. CRC Press, Chapman & Hall
Summary (Take-Home Messages)
5 Amino acids are divided into
proteinogenic and non-proteinogenic
amino acids. 20 proteinogenic amino
acids are found in the proteins.
5 Humans must take up some amino acids
with their diet, so-called essential amino
acids, because they cannot produce them
their selves.
5 α-amino acids have the general formula
R-CH(NH 2 )COOH. Most α-amino acids
have uncharged aliphatic or aromatic
residues R. Aspartic and glutamic
acids also contain another carboxyl
group; the three amino acids lysine,
arginine and histidine contain other
nitrogen-containing groups and are
positively charged at pH 7.
5 Amino acids are produced either by
protein hydrolysis, by chemical or
enzymatic synthesis or by fermentation.
5 Non-proteinogenic amino acids include
l-thyroxine, diiodtyrosine (DIT) and
l-Dopa, a precursor of dopamine. It is
used to treat Parkinson’s disease.
5 Peptides are divided into low-molecular
weight oligopeptides and higher
molecular weight polypeptides. From a
molecular mass of approx. 12,000 Dalton,
one speaks of proteins.
5 Important peptides include the synthetic
sweetener aspartame, the hormone
insulin, which regulates blood sugar
levels, and the pharmaceutically active
penicillins and cephalosporins.
5 In the case of proteins, a distinction is
made between simple and compound
proteins, which contain additional
prosthetic groups such as carbohydrates
or lipids.
5 The molecular masses of the proteins
range from 12,000 to one million Dalton.
5 Proteins are divided into primary,
secondary, tertiary and quaternary
structures. The structure is decisive for
the biological function of the proteins.
5 Fibrillary proteins (sclerotic or fibrous
proteins) have a leaflet structure and are
important for the stability and protection
of the organism because of their
14.3 · Proteins