The succinate dehydrogenase complex showing several cofactors, including flavin, iron–sulfur centers, and heme.
A representation of the 3D structure of the protein myoglobin showing turquoise α-helices. This protein was the first to have its structure solved by X-ray crystallography. Toward the right-center among the coils, a prosthetic group called a heme group (shown in gray) with a bound oxygen molecule (red).
A simple [Fe2S2] cluster containing two iron atoms and two sulfur atoms, coordinated by four protein cysteine residues.
John Kendrew with model of myoglobin in progress
Yeast ring used by Swedish farmhouse brewers in the 19th century to preserve yeast between brewing sessions.
The redox reactions of nicotinamide adenine dinucleotide.
Chemical structure of the peptide bond (bottom) and the three-dimensional structure of a peptide bond between an alanine and an adjacent amino acid (top/inset). The bond itself is made of the CHON elements.
Bubbles of carbon dioxide forming during beer-brewing
Resonance structures of the peptide bond that links individual amino acids to form a protein polymer
Yeast in a bottle during sparkling wine production at Schramsberg Vineyards, Napa
A ribosome produces a protein using mRNA as template
A block of compressed fresh yeast
The DNA sequence of a gene encodes the amino acid sequence of a protein
Active dried yeast, a granulated form in which yeast is commercially sold
The crystal structure of the chaperonin, a huge protein complex. A single protein subunit is highlighted. Chaperonins assist protein folding.
Diagram showing a yeast cell
Three possible representations of the three-dimensional structure of the protein triose phosphate isomerase. Left: All-atom representation colored by atom type. Middle: Simplified representation illustrating the backbone conformation, colored by secondary structure. Right: Solvent-accessible surface representation colored by residue type (acidic residues red, basic residues blue, polar residues green, nonpolar residues white).
Gram stain of Candida albicans from a vaginal swab. The small oval chlamydospores are 2–4 µm in diameter.
Molecular surface of several proteins showing their comparative sizes. From left to right are: immunoglobulin G (IgG, an antibody), hemoglobin, insulin (a hormone), adenylate kinase (an enzyme), and glutamine synthetase (an enzyme).
A photomicrograph of Candida albicans showing hyphal outgrowth and other morphological characteristics
The enzyme hexokinase is shown as a conventional ball-and-stick molecular model. To scale in the top right-hand corner are two of its substrates, ATP and glucose.
Ribbon diagram of a mouse antibody against cholera that binds a carbohydrate antigen
Proteins in different cellular compartments and structures tagged with green fluorescent protein (here, white)
Constituent amino-acids can be analyzed to predict secondary, tertiary and quaternary protein structure, in this case hemoglobin containing heme units

A cofactor is a non-protein chemical compound or metallic ion that is required for an enzyme's role as a catalyst (a catalyst is a substance that increases the rate of a chemical reaction).

- Cofactor (biochemistry)

Some proteins have non-peptide groups attached, which can be called prosthetic groups or cofactors.

- Protein

They noticed that adding boiled and filtered yeast extract greatly accelerated alcoholic fermentation in unboiled yeast extracts.

- Cofactor (biochemistry)

For instance, yeast proteins are on average 466 amino acids long and 53 kDa in mass.

- Protein

Nutritional yeast in particular is naturally low in fat and sodium and a source of protein and vitamins as well as other minerals and cofactors required for growth.

- Yeast

Yeast extract, made from the intracellular contents of yeast and used as food additives or flavours. The general method for making yeast extract for food products such as Vegemite and Marmite on a commercial scale is heat autolysis, i.e. to add salt to a suspension of yeast, making the solution hypertonic, which leads to the cells' shrivelling up. This triggers autolysis, wherein the yeast's digestive enzymes break their own proteins down into simpler compounds, a process of self-destruction. The dying yeast cells are then heated to complete their breakdown, after which the husks (yeast with thick cell walls that would give poor texture) are removed. Yeast autolysates are used in Vegemite and Promite (Australia); Marmite (the United Kingdom); the unrelated Marmite (New Zealand); Vitam-R (Germany); and Cenovis (Switzerland).

- Yeast
The succinate dehydrogenase complex showing several cofactors, including flavin, iron–sulfur centers, and heme.

2 related topics with Alpha


The enzyme glucosidase converts the sugar maltose into two glucose sugars. Active site residues in red, maltose substrate in black, and NAD cofactor in yellow.


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The enzyme glucosidase converts the sugar maltose into two glucose sugars. Active site residues in red, maltose substrate in black, and NAD cofactor in yellow.
Eduard Buchner
Enzyme activity initially increases with temperature (Q10 coefficient) until the enzyme's structure unfolds (denaturation), leading to an optimal rate of reaction at an intermediate temperature.
Organisation of enzyme structure and lysozyme example. Binding sites in blue, catalytic site in red and peptidoglycan substrate in black.
Enzyme changes shape by induced fit upon substrate binding to form enzyme-substrate complex. Hexokinase has a large induced fit motion that closes over the substrates adenosine triphosphate and xylose. Binding sites in blue, substrates in black and Mg2+ cofactor in yellow.
Chemical structure for thiamine pyrophosphate and protein structure of transketolase. Thiamine pyrophosphate cofactor in yellow and xylulose 5-phosphate substrate in black.
The energies of the stages of a chemical reaction. Uncatalysed (dashed line), substrates need a lot of activation energy to reach a transition state, which then decays into lower-energy products. When enzyme catalysed (solid line), the enzyme binds the substrates (ES), then stabilizes the transition state (ES‡) to reduce the activation energy required to produce products (EP) which are finally released.
The metabolic pathway of glycolysis releases energy by converting glucose to pyruvate via a series of intermediate metabolites. Each chemical modification (red box) is performed by a different enzyme.
In phenylalanine hydroxylase over 300 different mutations throughout the structure cause phenylketonuria. Phenylalanine substrate and tetrahydrobiopterin coenzyme in black, and Fe2+ cofactor in yellow.
Hereditary defects in enzymes are generally inherited in an autosomal fashion because there are more non-X chromosomes than X-chromosomes, and a recessive fashion because the enzymes from the unaffected genes are generally sufficient to prevent symptoms in carriers.

Enzymes are proteins that act as biological catalysts (biocatalysts).

A few decades later, when studying the fermentation of sugar to alcohol by yeast, Louis Pasteur concluded that this fermentation was caused by a vital force contained within the yeast cells called "ferments", which were thought to function only within living organisms.

In some enzymes, no amino acids are directly involved in catalysis; instead, the enzyme contains sites to bind and orient catalytic cofactors.

Simplified view of the cellular metabolism


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Set of life-sustaining chemical reactions in organisms.

Set of life-sustaining chemical reactions in organisms.

Simplified view of the cellular metabolism
Structure of adenosine triphosphate (ATP), a central intermediate in energy metabolism
Structure of a triacylglycerol lipid
This is a diagram depicting a large set of human metabolic pathways.
Glucose can exist in both a straight-chain and ring form.
Structure of the coenzyme acetyl-CoA.The transferable acetyl group is bonded to the sulfur atom at the extreme left.
The structure of iron-containing hemoglobin. The protein subunits are in red and blue, and the iron-containing heme groups in green. From.
A simplified outline of the catabolism of proteins, carbohydrates and fats
Mechanism of ATP synthase. ATP is shown in red, ADP and phosphate in pink and the rotating stalk subunit in black.
Plant cells (bounded by purple walls) filled with chloroplasts (green), which are the site of photosynthesis
Simplified version of the steroid synthesis pathway with the intermediates isopentenyl pyrophosphate (IPP), dimethylallyl pyrophosphate (DMAPP), geranyl pyrophosphate (GPP) and squalene shown. Some intermediates are omitted for clarity.
Effect of insulin on glucose uptake and metabolism. Insulin binds to its receptor (1), which in turn starts many protein activation cascades (2). These include: translocation of Glut-4 transporter to the plasma membrane and influx of glucose (3), glycogen synthesis (4), glycolysis (5) and fatty acid synthesis (6).
Evolutionary tree showing the common ancestry of organisms from all three domains of life. Bacteria are colored blue, eukaryotes red, and archaea green. Relative positions of some of the phyla included are shown around the tree.
Metabolic network of the Arabidopsis thaliana citric acid cycle. Enzymes and metabolites are shown as red squares and the interactions between them as black lines.
Aristotle's metabolism as an open flow model
Santorio Santorio in his steelyard balance, from Ars de statica medicina, first published 1614

The three main purposes of metabolism are: the conversion of the energy in food to energy available to run cellular processes; the conversion of food to building blocks for proteins, lipids, nucleic acids, and some carbohydrates; and the elimination of metabolic wastes.

These group-transfer intermediates are called coenzymes.

Here, organisms such as yeast, plants or bacteria are genetically modified to make them more useful in biotechnology and aid the production of drugs such as antibiotics or industrial chemicals such as 1,3-propanediol and shikimic acid.