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Lipids (Lipid Signals, Cofactors, Pigments (Steroid Hormones (Structure…

- - - - glycerophospholipids #
    - - PIP2 in inner membrane is a messenger molecule reservoir
        vasopression activates phospholipase C
        
        inositol phospholipids are points of nucleation for proteins to form multi-enzyme signaling complexes
        
        signaling proteins bind PIP3
      - PI Cascade
        
        Hormone binds to 7 trans-membrane receptor (7Tm)
        
        occupied 7Tm causes GDP-GTP exchange on Gqa
        
        Gqa with bound GTP activates PLC
        
        PLC cleaves PIP2 to IP3 and diacylglycerol
        
        1 more item...
  - - - FA derivatives of arachidonate/arachidonic acid and eicosapentaenic acid
        
        20:4 (delta5,8,11,14) and 20:5 (delta5,8,11,14,17) #
    - - reproductive function, fever, pain, inflammation, blood clotting, gastric acid secretion
        
        paracrine hormones that act on nearby cells instead of distal ones
      - Prostaglandins, PG
        
        Structure
        
        contain a 5 C ring
        
        PGE2 and other series 2 PGs come from arachidonate
        
        series 3 come from EPA
        
        Function
        
        series 3 elevate body temp, inflammation, and pain
        
        contract smooth muscle (uterus), stimulate blood flow to organs, sleep-wake cycle, tissue response to hormones
      - Thromboxanes, TX
        
        Structure
        
        6 C ring with ether bridge
        
        Function
        
        produced by platelets
        
        act in blood clotting and reduce blood flow
        
        NSAIDs inhibit PH H2 synthase
        
        catalyzes arachidonate to PGE2s and TXs
      - Leukotrienes, LT
        
        Structure
        
        3 conjugated DBs
        
        Function
        
        LT D4 from LT A4 induces smooth muscle contraction of airways
        
        inhibited by prednisone
      - Lipoxins, LP
        
        Structure
        
        linear eicosanoids with several hydroxyls on chain
        
        Function
        
        anti-inflammatory agents that are stimulated by aspirin
  - - - oxidized sterol derivatives
        
        have sterol nucleus but lack alkyl chain on D ring of cholesterol
        
        more polar than cholersterol
    - - move through blood on protein carriers to distal tissue
        
        bind tightly to highly specific receptors to change gene expression and metabolism
    - - volatile substances secreted by plants
        
        attract pollinators, repel herbivores, communicate with other plants
        
        made from FAs or isoprene condensations
  - - - A
        
        A = all-trans-retinol
        
        essential to vision, immunity, reproduction
        
        oxidized to retinoic acid and retinal
        
        control development, cell growth and differentiation, vision
        
        A1/carotene controls embryonic development, cell differentiation and proliferation
        
        retinal binds opsion to form photoreceptor pigment rhodopsin
        
        deficiency in pregnant women causes stunted growth and congenital malformation
      - D
        
        D3 = cholecalciferol
        
        formed in skin from UV-driven photochemical reaction
        
        converted to active calcitrol by liver and kidneys
        
        regulates calcium uptake in intestine and Ca levels in kidney and bone
        
        deficiency leads to rickets
        
        calcitrol regulates gene expression
    - - E
        
        class of lipids called tocopherols
        
        substituted aromatic ring and isoprenoid side chain
        
        hydrophobic association with cell membrane, lipid deposits, and lipoproteins in blood
        
        biological antioxidants
        
        aromatic ring destroys ROSs
        
        deficiency causes scaly skin, muscle wasting, sterility
      - K
        
        has an aromatic ring that undergoes a redox cycle during prothrombin formation
        
        K1 = phylloquinone
        
        K2 - menaquinone
        
        made by bactera
        
        ubiquinone and plastoquinone are electron carriers
        
        K aromatic ring redox
        
        prothrombin
        
        thrombin
        
        fibrinogen
        
        fibrin
        
        blood clots
  - - - isoprenoid alcohols are added to sugars to activate them before their addition to glycoproteins/lipids
    - - easily excited by visible light
        
        make birds colorful
        
        synthesized from isoprene
    - - secondary metabolites that act as antibiotics, antifungals, or cholesterol synthesis inhibitors
  - - - ceramides and sphingolipids #
    - - ceramide and sphingomyelin are protein kinase regulators
        
        involved in cell division, differentiation, migration, apoptosis
- - - - Structure
        
        one/two Gal residues connected by glycosidic linkage to C-3 of 1,2-diacylglycerol
        
        sulfolipids have a sulfonated Glc joined to diacylglycerol
      - Function
        
        localized to internal membrane of chloroplasts
        
        sulfonate is negatively charged like phosphate
        
        make up for limited soil phosphate
  - - - long (32-C) chain branched hydrocarbons linked at each end to a glycerol
        
        can span the entire plasma membrane
        
        twice as long as phospho/sphingolipids
        
        polar head group at each end
        
        glycerol linked to phosphate or sugars
    - - ether bond is much more stable against hydrolysis at low pH and high temps
    - - called glycerol dialkyl glycerol tetraethers
  - - - Structure
        
        two FAs ester linked to glycerol with phosphodiester polar/charged head group on third C of glycerol
        
        glycerol is prochiral
        
        parent compound is phosphatidic acid
        
        head group has phosphate negative at neutral pH and alcohol may be positive/negative/neutral
        
        cardiolipin has two phosphatidic acids with the same head group
      - Function
        
        Ether-Linked FAs
        
        Structure
        
        have an ether-link instead of an ester-link
        
        may have a DB at C1 like plasmalogen or be saturated
        Function
        
        plasmalogen is found in heart tissue
        
        platelet-activation factor is released from basophils
        
        stiumlates platelet aggregation, serotonin release, inflammation, allergic response
        
        smooth muscle, heart, uterus, lung tissues
      - Nomenclature
        
        named as derivatives of phosphatidic acid according to polar alcohol in head group
        
        ex. phosphatidylethanolamine has an ethanolamine
      - Phosphatidic acid = PA
        
        phosphatidylethanolamine = P
        
        choline = PC
        
        serine = PS
        
        glycerol =PG
        
        myo-inositol 4,5-bisphosphate = PI, PIP, PIP2, PIP3
        
        phosphatidylglycerol = cardiolipin #
    - - Structure
        
        polar head group with two nonpolar tails
        
        no glycerol
        
        one molecule sphingosine, one long-chain FA, and a polar head group joined by glycosidic or phosphodiester linkage
        
        if it is a phosphodiester it is a phospholipid
        
        C's 1-3 of sphingosine are analogous to 1-3 of glycerol
        
        FA attached via amide link to sphingosine = ceramide
      - Function
        
        recognition sites on neuron surfaces
        
        gangliosides determine blood type
      - Sphingomyelins
        
        contain a phosphocholine/phosphoethanolamine as the polar head group
        
        similar to phosphatidylcholines in structure and function
        
        no net charge on head group
      - Glycosphongolipids
        
        head group with 1+ sugars attaced to OH at C1 of ceramide (ether)
        
        no phosphate
        
        outer face of plasma membrane
        
        Cerebrosides
        
        in plasma membrane of neural tissue
        
        single sugar linked to ceramide
        
        Gal sugar in neural tissue
        
        Globosides
        
        2+ sugars
        
        usually Gal, Glc, or GalNAc
      - Gangliosides
        
        oligosaccharide polar head groups & 1+ Neu5Ac (sialic acid) residues
        
        negative charge at pH 7
        
        GM series, GD series, GT, GQ, etc
        
        determine blood types, fetal cell development, tumor formation
        
        neuronal tumor cells have few gangliosides
        
        cholera attacks them
  - - - steroid nucleus made of four fused rings
        
        three with 6 Cs and one with 5 Cs
        
        planar and rigid
        
        amphipathic with polar head and nonpolar body
        
        synthesized from isoprene subunits
    - - in eukaryotes and fungi, not bacteria
        
        precursor for steroid hormones and bile acids
        
        bile acids emulsify fats in intestines
- - - - carboxylic acid with carbon chain 4-36 C
        
        double bonds, commonly at C9, C12 and C15
        
        cis DBs almost always unconjugated
    - - Structure
        
        three FAs in an ester linkage with glycerol
        
        simple all have same FA, complex have different ones
        
        most natural ones are mixed
        *nonpolar hydrophobic with low water solubility
        
        melting point depends on mix of FAs
        
        more long-chain FAs = higher MP
      - Function
        
        form fat droplets in cells
        
        store twice as much energy than carbs
        
        unhydrated, saves space
        
        require lipases to release FAs
      - Nomenclature
        
        20:2 (delta^9,12) = 20-C chain with two DBs at 9 & 12
        
        cis-cis-9,12-icosadienoic acid
        
        n-whatever acid = saturated
        
        PUFAs are named from the last (omega) C
    - - Structure
        
        esters of long chain FAs with long chain alcohols
        
        high melting points
      - Function
        
        protect hair and skin
        
        prevent water saturation or evaporation
    - - longer saturated chains decrease solubility
        
        unsatured DBs have a lower melting point
        
        cis DB causes kink