Microbiology and Immunology

Biodegradable substances WORLD OF MICROBIOLOGY AND IMMUNOLOGY

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Chemistry Prize was shared by three scientists: the American

Paul Boyer and the British J. Walker for their discovery of the

“rotary engine” that generates the energy-carrying compound

ATP, and the Danish J. Skou, for his studies of the “pump” that

drives sodium and potassium across membranes. In the same

year, the Prize in Medicine and Physiology went to Stanley

Prusiner, for his studies on the prion, the agent thought to be

responsible for “mad cow disease” and several similar human

conditions.

Biochemistry draws on its major themes from many

disciplines. For example from organic chemistry, which

describes the properties of biomolecules; from biophysics,

which applies the techniques of physics to study the struc-

tures of biomolecules; from medical research, which increas-

ingly seeks to understand disease states in molecular terms

and also from nutrition, microbiology, physiology, cell biol-

ogy and genetics. Biochemistry draws strength from all of

these disciplines but is also a distinct discipline, with its own

identity. It is distinctive in its emphasis on the structures and

relations of biomolecules, particularly enzymesand biologi-

cal catalysis, also on the elucidation of metabolic pathways

and their control and on the principle that life processes can,

at least on the physical level, be understood through the laws

of chemistry. It has its origins as a distinct field of study in the

early nineteenth century, with the pioneering work of

Freidrich Wöhler. Prior to Wöhler’s time it was believed that

the substance of living matter was somehow quantitatively

different from that of nonliving matter and did not behave

according to the known laws of physics and chemistry. In

1828 Wöhler showed that urea, a substance of biological ori-

gin excreted by humans and many animals as a product of

nitrogen metabolism, could be synthesized in the laboratory

from the inorganic compound ammonium cyanate. As Wöhler

phrased it in a letter to a colleague, “I must tell you that I can

prepare urea without requiring a kidney or an animal, either

man or dog.” This was a shocking statement at the time, for it

breached the presumed barrier between the living and the

nonliving. Later, in 1897, two German brothers, Eduard and

Hans Buchner, found that extracts from broken and thor-

oughly dead cells from yeast, could nevertheless carry out the

entire process of fermentationof sugar into ethanol. This dis-

covery opened the door to analysis of biochemical reactions

and processes in vitro (Latin “in glass”), meaning in the test

tube rather than in vivo, in living matter. In succeeding

decades many other metabolic reactions and reaction path-

ways were reproduced in vitro, allowing identification of

reactants and products and of enzymes, or biological cata-

lysts, that promoted each biochemical reaction.

Until 1926, the structures of enzymes (or “ferments”)

were thought to be far too complex to be described in chemi-

cal terms. But in 1926, J.B. Sumner showed that the protein

urease, an enzyme from jack beans, could be crystallized like

other organic compounds. Although proteins have large and

complex structures, they are also organic compounds and

their physical structures can be determined by chemical

methods.

Today, the study of biochemistry can be broadly

divided into three principal areas: (1) the structural chemistry

of the components of living matter and the relationships of

biological function to chemical structure; (2) metabolism, the

totality of chemical reactions that occur in living matter; and

(3) the chemistry of processes and substances that store and

transmit biological information. The third area is also the

province of molecular genetics, a field that seeks to under-

stand heredity and the expression of genetic information in

molecular terms.

Biochemistry is having a profound influence in the

field of medicine. The molecular mechanisms of many dis-

eases, such as sickle cell anemia and numerous errors of

metabolism, have been elucidated. Assays of enzyme activity

are today indispensable in clinical diagnosis. To cite just one

example, liver disease is now routinely diagnosed and moni-

tored by measurements of blood levels of enzymes called

transaminases and of a hemoglobin breakdown product called

bilirubin. DNAprobes are coming into play in diagnosis of

genetic disorders, infectious diseases and cancers.

Genetically engineered strains of bacteriacontaining recom-

binant DNA are producing valuable proteins such as insulin

and growth hormone. Furthermore, biochemistry is a basis for

the rational design of new drugs. Also the rapid development

of powerful biochemical concepts and techniques in recent

years has enabled investigators to tackle some of the most

challenging and fundamental problems in medicine and phys-

iology. For example in embryology, the mechanisms by

which the fertilized embryo gives rise to cells as different as

muscle, brain and liver are being intensively investigated.

Also, in anatomy, the question of how cells find each other in

order to form a complex organ, such as the liver or brain, are

being tackled in biochemical terms. The impact of biochem-

istry is being felt in many areas of human life through this

kind of research, and the discoveries are fuelling the growth

of the life sciences as a whole.

See alsoAntibody-antigen, biochemical and molecular reac-

tions; Biochemical analysis techniques; Biogeochemical

cycles; Bioremediation; Biotechnology; Immunochemistry;

Immunological analysis techniques; Miller-Urey experiment;

Nitrogen cycle in microorganisms; Photosynthesis

BBiodegradable substancesIODEGRADABLE SUBSTANCES

The increase in public environmental awareness and the

recognition of the urgent need to control and reduce pollution

are leading factors in the recent augment of scientific research

for new biodegradable compounds. Biodegradable com-

pounds could replace others that harm the environment and

pose hazards to public health, and animal and plant survival.

Biodegradation, i.e., the metabolization of substances by bac-

teria, yeast, fungi, from which these organisms obtain nutri-

ents and energy, is an important natural resource for the

development of new environmental-friendly technologies with

immediate impact in the chemical industry and other eco-

nomic activities. Research efforts in this field are two-fold: to

identify and/or develop transgenic biological agents that

digest specific existing compounds in polluted soils and water,

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