GLYCERALDEHYDE: STRUCTURE, CHARACTERISTICS, FUNCTIONS - BIOLOGY - 2024

The glyceraldehyde is the only three - carbon monosaccharide, which at the time the only triose. It is also an aldotriose because it has an aldehyde group. The word glyceraldehyde comes from the combination of glycerin and aldehyde. This is because glyceraldehyde is similar to glycerin, but carbon one (C-1) is an aldehyde.

The chemical synthesis of glyceraldehyde is carried out by different methods, for example using enzymes. Glyceraldehyde is a fairly reactive molecule, being able to form crosslinks between proteins.

Source: DrTW at Dutch Wikipedia

Structure

Glyceraldehyde possesses an asymmetric or chiral center (the carbon atom 2, C-2). It forms two enantiomers D (right-handed) and L (left-handed), which rotate the plane of polarized light in opposite directions: D-glyceraldehyde turns it to the right and L-glyceraldehyde to the left.

The specific optical rotation of D-glyceraldehyde, at 25 ºC, is + 8.7º, and the specific optical rotation of D-glyceraldehyde, at 25 ºC, is -8.7º. D-glyceraldehyde is frequently found in nature, mainly as glyceraldehyde 3-phosphate.

The L-glyceraldehyde configuration is used as a standard reference for carbohydrates. D-sugars abound in biological molecules. The carbon 3 (C-3) atom of glyceraldehyde is a hydroxymethylene group (-CH ₂ OH).

characteristics

Glyceraldehyde crystals are colorless and taste sweet. The empirical formula of this sugar is C ₃ H ₆ O ₃ and its molecular weight is 90 g / mol.

In aqueous solution, DL-glyceraldehyde is mainly present as aldehydrole, which is a hydrated form of the aldehyde. Crystalline DL-glyceraldehyde is dimeric.

Analysis of glyceraldehyde crystals by X-rays has shown that they possess 1,4-dioxane rings with all substituents in the equatorial orientation.

In aqueous solution, glyceraldehyde undergoes autoxidation generating 1-hydroxyalkyl free radicals and dioxygen reducing intermediates such as superoxide, hydrogen peroxide, and hydroaxial radicals. This is associated with rapid oxygen consumption.

The rate of oxygen consumption slowly decreases in the presence of superoxide dismutase. This suggests that there is superoxide formation during the autoxidation of glyceraldehyde. The limiting step of glyceraldehyde autoxidation is the glyceraldehyde enolization rate

The synthesis of D-glyceraldehyde is catalyzed by primary and secondary amino acids, being favored at low pH values ​​(3 to 4).

Features

In cross-links between proteins

Protein-protein interaction is a molecular mechanism of multiple complex biological processes. These interactions can be transient, be the interaction of proteins in a metabolic pathway or the translation of the signal.

Chemical cross-links are a direct method for identifying transient and stable protein-protein interactions.

The technique of crosslinking between proteins consists of the formation of covalent bonds, for which agents that have bifunctional reactive groups that react with the amino and sulfhydryl groups of amino acid residues of proteins are used.

Specifically, the agents react with primary amino groups (such as the epsilon-amino of lysine residues) and form crosslinks both within a protein subunit and between protein subunits.

There are a wide variety of commercially available crosslinking agents. Although glyceraldehyde is a crosslinking agent, there are other more popular agents, such as glutaraldehyde. This is because glutaraldehyde maintains the structural rigidity of the protein, which is an important requirement in many studies.

Other popular agents are homobifunctional imidoesters, which vary in the length of the spacer arm between their reactive groups. Some examples of imidoesters are dimethyl apimidate (DMA), dimethyl suberimidate (DMS), and dimethyl pimilimidate (DMP).

In the cross-links between gelatin microspheres

Gelatin microspheres have the potential to serve for controlled drug release. This is because these microspheres are not toxic and their products are easily excreted. However, gelatin is a soluble polymer, so it must be chemically modified to serve as a drug delivery system.

D, L-glyceraldehyde can be considered a non-toxic cross-linking agent (the lethal dose, LD50 ip in rats is 2000 mg / kg). Furthermore, in the human body, D-glyceraldehyde is phosphorylated by triose kinase. In this way, glyceraldehyde 3-phosphate is formed that enters glycolysis.

Treatment of gelatin microspheres with D, L-glyceraldehyde for 24 hours produces microspheres with a reduced number of free lysine amino acid residues. Therefore, the ability of the microspheres to prolong, for example, the effect of clodinine hydrochloride, which is antihypertensive, has been evaluated.

The microspheres were administered by subcutaneous injection to albino guinea pigs and rats. After the injection, systolic blood pressure decreased for two hours, subsequently recovering its baseline value. Injection site tissues were analyzed and no microspheres were found, although inflammation was observed.

In prebiotic reactions

Under prebiotic conditions - such as those assumed by the early Earth - formaldehyde could have served for the synthesis of glyceraldehyde, a chemical intermediate involved in the chemical processes that could have originated life.

The previous hypothesis is based on the fact that both glycolysis and photosynthesis have glyceraldehyde 3-phosphate as a metabolic intermediate.

A chemical model has been proposed that explains the biosynthesis of glyceraldehyde from formaldehyde by a cyclic pathway. The synthesis of glyceraldehyde takes place by adding formaldehyde to a triose (glyceraldehyde ↔ dihydroxyacetone) to produce a tetrose (ketotetrose ↔ aldotetrose), producing glycoaldehyde, a precursor of glyceraldehyde.

The addition of formaldehyde to the glycoaldehyde completes the cycle. The synthesis of two molecules of triose occurs from six molecules of formaldehyde.

In general, prebiotic synthesis of sugars is believed to be involved in the Formosa reaction, in which formaldehyde in the presence of a small amount of glycoaldehyde is converted to sugars by aldol condensation reactions.

It has been proposed that the prebiotic oxidation of sugars (glycoaldehyde, trioses, tetroses) produced polyhydroxyacids that act as autocatalytic substances.

The conversion of glyceraldehyde into lactic acid and glyceric acid, an oxide dependent on iron hydroxide, suggests that the oligoesters of these hydroxy acids took place on the surface of this material.

References

1. Breslow, R., Ramalingam, V., Appayee, C. 2013. Catalysis of glyceraldehyde synthesis by primary or secondary amino acids under prebiotic conditions as a function of pH. Origin Life Evolution Biosphera. DOI 10.1007 / s11084-013-9347-0.
2. Carey, FA, Giuliano, RM 2016. Organic chemistry. McGraw-Hill, New York.
3. Robyt, JF 1998. Essentials of Carbohydrate Chemistry. Springer, New York.
4. Thornalley, P., Wolff, S., Crabbe, J., Stern, A. 1984. The autoxidation of glyceraldehyde and other simple monosaccharides under physiological conditions catalyzed by buffer ions. Biochimica et Biophysica Acta, 797, 276–287.
5. Vandelli, MA, Rivas, F., Guerra, P., Forni, F., Arletti, R. 2001. Gelatin microspheres crosslinked with D, L-glyceraldehyde as a potential drug delivery system: preparation, characterization, in vitro and in vivo studies. International Journal of Pharmaceutics, 215, 175–184.
6. Weber, AL 1987. The triose model: glyceraldehyde as a source of energy and monomers for prebiotic condensation reactions. Origins of Life, 17, 107-119.