Types of Lipids VII

Suaib Luqman

epgp books

 

  1. Objectives
  • v To know about the prenol glycosides
  • v What are the significance of lipids with amino acid
  • v Importance & Significance of Derived or Precursor Lipids
  1. Concept Map

 

  1. Description

3.1 Types of Lipids IV

 

Complex Lipids

 

 

Prenol glycosides

 

In Nicotiana, Capsicum, and Lycium, hydroxygeranyllinallol diterpenoid glycosides are copious metabolites includes 1-2 acyclic geranyllinalool aglycones coupled to one or more sugar units. Based on the below mentioned chemical structures of R1 and R2, several analogues have been isolated.

Structure of Hydroxygeranyllinallol diterpenoid glycoside from Nicotiana obtusifolia

Plakopolyprenoside

It is a cytotoxicity glycolipid poised with C35 linear polyprenyl alcohol and a dixylosyl chain of carbohydrate extorted from Plakortis simplex (marine sponge). Plaxyloside, an analogous compound, is made up of six xylopyranose units as carbohydrate chain.

 

Glycosyl phosphopolyprenols

 

 

They are modest phosphorylated glycolipids act as co-enzymes of glycosyl transferases (membrane bound) and transfer glycosyl dregs from nucleoside diphosphate sugars to proteins (acceptors). In bacteria and other prokaryotes, glycosyl phosphopolyprenols are implicated in the genesis of cell wall complex polysaccharides whereas in eukaryotes they are concerned with the protein N-glycosylation process. In fungi and yeasts, they work in protein O-mannosylation whilst in plants their functions also cover the glucans formation. Naturally, monophosphoryl & diphosphoryl (derivatives of polyprenols) have been established primarily concerned with monosaccharide transfer and as an intermediate in the oligosaccharide units assembly. In bacteria, the lipid moiety is formed by polyisoprenoids (10-12 isoprenoid units) and in mammals and plants by dolichols (18-22 isoprenoid units) and ficaprenols respectively

 

Phenolic glycolipids (Mycosides)

 

 

Smith et al. (1954) portrayed glycolipids (mycosides) from the immunizing fractions of Mycobacterium tuberculosis extracts using IR spectroscopy. It comprises different structures such glycopeptidolipids and phenolglycolipids (glycosides of phenolphthiocerol dimycocerosate). Further work on structure specifies an oligosaccharide moiety associated to a phenolphthiocerol iota esterified by mycoserosic acids, hence establishing phthiocerol waxes. The mycoside family of complex phenolic glycolipids has the common formula shown underneath:

A variety of mycoside family of complex phenolic glycolipids have different oligosaccharide moiety and diverse compositions of fatty acid. Mycoside A (Mycobacterium kansasii) contains 2,6-dideoxy-4-methyl Arap-2-methyl acetyl Fucp-2-methylRhap-2-methyl-Rhap. Mycoside B (Mycobacterium tuberculosis) contains 2-O-methylrhamnose. Other includes two molecules of methyl rhamnopyranose and methyl glucopyranose. They are immunogenic with sugars at the non-reducing end and the acquaintance has change the serological diagnosis of leprosy. The phenolic glycolipid from Mycobacterium leprae bears the inimitable determinant 3,6-di-O-Me-  b-D-Glcp-2,3-di-0- Me-a-L-Rhap, a highly reactive and explicit for sera from the lepromatous patients of leprosy.

 

  1. Glycopeptidolipids (glycosylated fatty acylated peptides)

Rhizochalin (a two-headed sphingolipids allied to a galactose moiety) has been established in Rhizochalina incrusta (marine sponges). Besides, cytotoxic and antimicrobial properties, few analogues (2-ethyl carbamate of rhizochaline) were also revealed to be anti-carcinogenic and pro-apoptotic agents

Mycoside C, a monoglycosylated fatty acylated peptide customized by capricious oligosaccharides liable for the sero specificity of all immunotypes present in M. scrofulaceum/ M. intracellulare/ M. avium/ complex. In 1979, Brennan et al., redefine the structures of glycopeptidolipids recognized by some groups of French investigators during 1967-1971.

Glycopeptides have the indispensable tetrapeptide core (Phe-aThr-Ala-alaninol connected to a rhamnose cluster) but vary in the glycosyl residue connect to the threonyl group (1-6 units). The fatty acyl substituent composed of 3-hydroxy/3-methoxy type and a 28 carbon units. In M. xenopi, a second family of alkali-labile serine-containing glycopeptidolipid has been discovered which differs from mycosides C.

 

Myxotyrosides, an unusual glycopeptidolipids bearing rhamnose have been isolated from Myxococcus sp. with an iso-branched or a normal fatty acid amide allied to a glycosylated tyrosine-derived structure.

 

Lipoamino acid

 

Are lipids with solitary amino acid connected to a long-chain acids and alcohol but without phosphate group. They are present solely in bacteria and lower plants (algae, protozoa, fern) and occasionally named lipoamino acids. Two complex groups of lipoamino acids have been identified and are as under:

 

N-acyl and/or ester linkages bearing lipids having an amino acid

Various kinds of derivatives are recognized as per their amino acid moiety:

  1. Lysine-containing lipids: Example is Siolipin A where lysine is N-linked to a fatty acid (R1 hydroxylated or normal) and to an ester link fatty alcohol (R2), present in Streptomyces species.
  1. Ornithine-containing lipids: Ornithine through an amide bond is connected to a fatty acid (R1) and by an ester bond to a long-chain fatty alcohol (R2). The R1 chain has 16-18 carbon moieties and the fatty alcohol have a cyclopropane ring. They are found in photosynthetic purple bacteria, Gram negative bacteria and in few Gram positive (Streptomyces and Mycobacterium species) but absent in Eukarya and Archaea. The 3 hydroxy fatty acyl group is appended to α amino group of ornithine and a second fatty acyl group is ester linked to the 3 hydroxy position of the first fatty acid.

 

  1. Glycine-containing lipids: They have been identified in Cytophaga johnsonae (gliding bacterium) and Cyclobacterium marinus (a sea water Gram negative bacterium). They contain two fatty acyl residues and an amino acid glycine by the acyl-oxyacyl structure. In C. marinus, an iso-3-hydroxyfatty acyl group of a N-[3-D-(13-methyltetradecanoyloxy)- 15-methylhexadecanoyl] glycine is connected by amide to glycine and its 3 hydroxy group is esterified to a different iso fatty acid.

Ether linkage lipids having a glycerol and an amino acid

 

 

They are primarily derived from homoserine (few have an alanine moiety) characteristic of algae. These lipids are also known as betain lipids (the polar head) derived from N,N,N-trimethyl glycine (betaine). In Ochromonas danica (yellow-green algae), the homoserine-derived lipids were first recognized accounting for more than 50% of total lipids created by an ether linkage between homoserine-diacylglycerol and are extensively strewn. During phosphate stress in Rhodobacter sphaeroides and Sinorhizobium meliloti, they were reported to be a replacement for phospholipids and induces the synthesis of diacylglyceryl-N,N,N-  trimethylhomoserine. It well documented in Arabidopsis and oat and parallel interpretation were also reported for ocean phytoplankton using lipids of non-phosphorus nature and in retort to scarcity of phosphorus.

 

Structure of diacylglyceryl-N,N,N-trimethylhomoserine

 

This type of lipid was also reported from Acanthamoeba (protozoa), Epidermophyton floccosum (fungus), Chlamydomonas, Ulva, Acetabularia, Closterium, Volvox (green algae), mushrooms, vascular cryptogamic plants but absent in Chlorella, Tetraselmis and seed plants.

 

R1, R2 (Acyl chains) are 18:0, 18:2 (n-6), 18:3 (n-6) or (n-3) in Dunaliella and 20:5 (n-3) in Chlorella minutissima and mainly 18:1 (n-9) in Acanthamoeba. Since they have a quaternary ammonium group, homoserine-derived lipids look like phosphatidylcholine in some reverence.

 

In Ochromonas danica, Diacylglyceryl hydroxymethyltrimethyl-b-alanine (Alanine-derived lipids) was first recognized and observed to swap the homoserine-derived lipids in brown algae but are absent in the green. In Pavlova lutheri, Diacylglyceryl carboxyhydroxymethylcholine, another betain lipid was later discovered.

 

In Mycobacterium phlei strain IST, a Lysine-containing diacylglycerol was isolated which is esterified to 1,2- diglyceride by an ester link and the foremost fatty acyl substitutions are tuberculostearic and palmitic acid.

 

Cerebroside: Also known as monoglycosylceramides, cerebrosides are lipids containing ceramides, carbohydrate (glucose or galactose), fatty acid, sphingosine but without phosphoric acid and glycerol. It is the common name for glycosphingolipids, an essential component in animal muscle and nerve cell membranes. A deficiency in deprivation of glucocerebrosides and galactocerebrosides results in Gaucher’s and Krabbe disease.

 

Ganglioside: Are lipids containing glycosphingolipid (ceramide), saccharide (glucose or galactose) with one or more sialic acids (NANA: n-acetylneuraminic acid) coupled to the sugar units. NANA creates the head groups of gangliosides anionic at pH 7, which discern them from globosides. In 1942, Ernst Klenk, a German Scientist gave the name ganglioside to lipids isolated from ganglion cells of the brain. They are constituents (>60 gangliosides are known) of the cell plasma membrane that modulates cell signal transduction. Gangliosides have also been  shown to be exceedingly vital molecules in immunology. Natural as well as semi-synthetic gangliosides are considered probable therapeutics for neurodegenerative disorders.

 

Cytolipids: Are lipids containing fatty acids, sphingosine, glucose or galactose.

 

 

Derived or Precursor Lipids

 

 

Are the substances produced from simple and compound lipids through the process of hydrolysis. There are many different types of derived lipids, including alcohols, carotenoids, diglycerides, fatty acids, ketone bodies, monoglycerides, steroids and terpenes. Since they are uncharged (acylglycerol), glycerides, cholesterol are termed Neutral Lipids.

 

  1. Hydrocarbons: Carotenoids and Squalene.
  2. Sterols: Cholesterol (Cholestane, Coprostane, Cholestonol, Coprostanol, Dehydrocholesterol, Lanosterol, Lathosterol, Agnosterol), Mycosterol (Sterol of Yeasts), Ergosterol (Sterol of fungus), Phytosterol (Sterol of Plants-Stigmasterol and Sitosterol), Bile acid (Cholic acid, Deoxycholic acid, Lithocholic acid, Glycocholic acid, Taurocholic acid, Cholanic acid).
  • Vitamins: Vitamin K (Menadione), Vitamin E (Tocopherol), Vitamin D (Cholecalciferol).

Module 05-11 brings in knowledge about types of lipids and representative of each type with a prominence on their role in physiological functions.

 

  1. Summary

 

 

In this lecture we learnt about:

 

  • The Types of Lipids with amino acid, prenyl glycosides
  • The Importance & Significance of Derived or Precursor Lipids

 

you can view video on Types of Lipids VII

Weblinks

 

Books

1.Biochemistry of Lipids: Biochemistry Series One by TW Goodwin. 2014. https://books.google.co.in/books?isbn=1483193977

2.Dictionary of Marine Natural Products with CD-ROM by John W Blunt, ‎Murray HG, Munro. 2007 https://books.google.co.in/books?isbn=0849382173

3.Outstanding Marine Molecules – Google Books Result by Stephane La Barre, ‎Jean-Michel Kornprobst. 2014. https://books.google.co.in/books?isbn=3527681531

4. The Lipid Handbook, Second Edition – Page 219 – Google Books Result by Frank D. Gunstone, John‎ L. Harwood, Fred‎ B. Padley. 1994. https://books.google.co.in/books?isbn=0412433206

5.  Cerebroside. https://books.google.co.in/books?id=L96tubUcx34C

6.Ganglioside Function: Biochemical and Pharmacological …by Giuseppe Porcellati. 2013. https://books.google.co.in/books?isbn=1461446147

Journals

  1. Shibaev VN1, Danilov LL.New developments in the synthesis of phosphopolyprenols and their glycosyl esters. Biochem Cell Biol. 1992 Jun; 70 (6): 429-37.
  2. Chatterjee D, Bozic CM, Knisley C, Cho SN, Brennan PJ. Phenolic glycolipids of Mycobacterium bovis: new structures and synthesis of a corresponding seroreactive neoglycoprotein. Infection and Immunity. 1989; 57 (2): 322-330.
  3. Makarieva TN, Guzii AG, Denisenko VA, Dmitrenok PS, Santalova EA, Pokanevich EV, Molinski TF, Stonik VA. Rhizochalin A, a novel two-headed sphingolipid from the sponge Rhizochalina incrustata. J Nat Prod. 2005 Feb; 68 (2): 255-7.
  4. Erich Baer, K. V. Jagannadha Rao. LIPOAMINO ACIDS: SYNTHESIS OF AMINO ACID ESTERS OF PHOSPHATIDYL GLYCEROLS. Canadian Journal of Biochemistry, 1966, 44(6): 899-915.