PROTEINS

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Author:
RolandoBijasa
ID:
305302
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PROTEINS
Updated:
2015-07-18 21:54:06
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biochem
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Biochemistry
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Lecture 2:Proteins
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  1. Make up about 15% of the cell
    Proteins
  2. Functions of protein
    [ESTCIHCS]

    • enzymes
    • structural
    • transport & storage
    • Cell signaling
    • immune protection
    • Hormones
    • Coordinated Motion
    • Special functions
  3. catalytic activity (amylase, lipase, pepsin)
    Enzyme
  4. collagen, α-Keratin, fibroin, elastin
    Structural
  5. Hb, ambumin, Mb
    Transport and storage
  6. Membrane receptors (insulin receptors)
    Cell Signaling
  7. immunoglobulins
    Immune protection
  8. Insulin, Glucagon
    hormones
  9. actin & myosin
    coordinated motion
  10. determines function or activity of proteins
    Shape or Conformation
  11. proteins are made of AA linked by ________
    Peptide Bond
  12. Repeating sequence of the N-Cα-C-N-Cα-C-N-Cα-C in peptide bond
    Polypeptide backbone
  13. nor part of backbone or the peptide bond
    side chain or R
  14. Classification of Protein
    • Simple
    • Conjugated
  15. composed only of amino acids
    Simple Proteins
  16. Example of Simple Proteins
    • albumin
    • histones
    • protamines
  17. Contains non-Protein Group (prosthetic group)
    Conjugated Proteins
  18. Example of conjugated proteins
    [NGLMPC]

    • nucleoproteins
    • glycoproteins
    • lipoproteins
    • metalloproteins
    • phosphoproteins
    • chromoproteins
  19. help determine the conformation in an aqueous solution
    side chain
  20. determined by the sequence of the amino acids
    Protein shape
  21. the final shape and has the lowest free energy possible
    conformation
  22. the process of unfolding the protein
    denaturation
  23. denaturing agents
    • heat
    • pH
    • chemical compounds (alcohol, urea, acids and base)
  24. 2 regular folding patterns
    • α-Helix
    • β-sheet
  25. proteins turns like a spiral-fibrous protein (hair, nails, horns)
    α-Helix
  26. proteins folds back on itself as in a ribbon-globular protein
    β-sheet
  27. core of many protein
    β-sheet
  28. form a rigid structure with H-bond
    β-sheet
  29. 2 types of β-sheet
    • Anti-parallel
    • Parallel
  30. run in opposite direction of its neighbors
    Anti-parallel
  31. run in the same direction with longer looping sections between them
    parallel
  32. formed by H-bond between every 4th peptide bond -C=O to N-H
    α-Helix
  33. Usually in proteins that span  a membrane (membrane proteins)
    α-Helix
  34. can coil to the right or left and around each other
    α-Helix
  35. a framework for structural proteins such as the hair, nails and skin
    coiled-coil shape
  36. types of protein shape
    • Globular Proteins
    • Fibrous Proteins
  37. soluble in water, compact shape like a ball with irregular surfaces
    globular proteins
  38. 2° structure is a mixture of α, β & loop structures
    globular proteins
  39. example of globular proteins
    ETIHM

    • Enzyme
    • Transport proteins
    • immunoglobulins
    • hormones
    • myoglobin
  40. usually span a long distance in the cell
    Fibrous Protein
  41. 3D structure is usually long and rod shaped, insoluble in water, structural function
    Collagen, Keratin, Silk fibroin, elastin
  42. a right handed alpha helix
    Alpha Keratin
  43. composed of a pair of coiled-coil
    Protofilament
  44. composed of 2 pairs of protofilaments or a microfilament
    Protofibrils
  45. composed of about four protofibrils or about 32 strands of α-keratin
    Intermediate Filament/ Microfibril
  46. an array of many α-keratin filaments
    strand of hair
  47. the key structural material making up the outer layer of human skin, and also a  key structural component of hair and nails
    Keratin
  48. basic structural unit of alpha keratin
    alpha helix
  49. found in horns and nails have more disulfide bonds
    Hard Keratins
  50. found in wools, hair and feather
    soft keratin
  51. Most abundant protein in the human body (25% of total protein weight of human body)
    collagen
  52. insoluble fibers that have high tensile strength
    Collagen
  53. consist of 3 α-chains of same size tightly wrapped around each other
    Collagen
  54. major structural material in tendons, cartilage, ligaments, blood vessels and skin, eye cornea, organic component of bone and teeth
    Collagen
  55. predominant structural features in collagen
    Triple helix
  56. a left handed with 3 AA residues per turn
    collagen alpha chain
  57. required at the tight junction where the 3 helices meet
    Glycine
  58. together with keratin,  is responsible for skin strength and elasticity
    Collagen Triple Helix
  59. produces a bend in the polypeptide chain, responsible for 2° structure of collagen
    Proline
  60. every 3rd AA is gly which bec of its small side chain is the only AA that can fit into the restricted space where the 3 heices meet
    1° structure
  61. beeding of gums, skin discoloration result from fragile collagen due to Vit C deficiency
    Scurvy
  62. are made up of collagen molecules aligned in a staggered fashion and cross-linked for strength
    Collagen fibrils
  63. abnormal bone formation in babies, Bones easily bend and fracture
    osteogenesis imperfecta/ Brittle bone Syndrome
  64. characterized by stretchy skin and loose joints
    Ehlers-Danlos syndrome
  65. deficiency in Ascorbic acid needed for hydroxylation of pro and lys, resulting collagen has decreased tensile strength
    Scurvy
  66. major protein component of tissues that require elasticity such as arteries, lungs, bladder, skin, and elastic ligaments and cartilages
    elastin
  67. composed of soluble tropoelastin protein containing primarily glycine and val and modified alanine and proline residues
    elastin
  68. a 65kDa protein that is highly cross-linked to form an insoluble complex
    tropoelastin
  69. with rubber-like properties, structure is irregular or a random coil
    elastin
  70. can be stretched to several times its normal length but recoil to its original shape when stretching force is relaxed
    elastin
  71. involves in cross-linking if elastin
    lysine
  72. the protein in silk, produced by insects and spiders
    Fibroin
  73. does not stretch bec it is already extended but it is flexible
    silk
  74. causes a total or partial loss of biological activity, loss of structure and function
    denaturation
  75. specific 3D conformation is changed by breaking some bonds without breaking its primary structure
    denaturation
  76. disruption of weak forces that stabilize proteins
    denaturation
  77. precipitation out of biochemical solutions of denatured proteins
    coagulation
  78. denatured completely by urea in the presence of a reducing agent
    ribonuclease A
  79. a hemoprotein only found in the cytoplasm of erythrocyte (RBC)
    hemoglobin
  80. transports O2 and CO2 bet lungs and various tissues
    hemoglobin
  81. Buffer a lot of Histidine
    hemoglobin
  82. a tetramer (2α & 2β)
    hemoglobin
  83. Binds O2 reversibly like Mb But binding is cooperative
    hemoglobin
  84. both α & β chains are strikingly similar to that of Mb
    hemoglobin
  85. normal concentration of Hb in blood
    • males 135 - 175 g/L
    • female 120-168 g/L
  86. predominant structure of Mb and Hb
    α-helix
  87. each globin contains:
    1 heme group with a central Fe2+ ion
  88. Heme structure
    metalloporphyrine (cyclic tetrapyrrole)
  89. heme contains
    • conjugated system of double bonds
    • photoporphyrine ring
    • 1 iron cation
  90. bound in the middle of tetrapyrrole skeleton by 4 coordination covalent bond
    iron cation
  91. coordination number of iron in heme
    6
  92. 6 bonds of iron in heme
    • 4N of 4 pyrrole rings
    • link to His F8
    • link to an O2
  93. reduces ferric acid to ferous
    Ascorbic acid
  94. Hemoproteins
    • hemoglobin
    • myoglobin
    • cytochromes
    • catalases
    • peroxidases
  95. hemoproteins that binds O2
    • Hemoglobin
    • myoglobin
  96. hemoproteins which is found in electron transport chain
    cytochromes
  97. hemoproteins which is an enzyme
    • catalases
    • peroxidases
  98. the 5th coordination bond of Fe is formed with
    His F8 (proximal)
  99. the 6th bond is for Ois formed with
    His E7 (Distal)
  100. which has stronger affinity
    Mb
  101. a single chain globular protein of 153 AA, containing 1 Heme group
    Mb
  102. transports oxygen in skeletal and heart muscles
    Mb
  103. found in cytosol within cells and marker of myocardial damage
    Mb
  104. stores oxygen in red muscle cell
    Mb
  105. 2α and 2β subunits
    Adult Hb (Hb A)
  106. Minor form of Hb in adults. it forms only 2-3% of a total Hb A (2α, 2δ)
    HbA2
  107. the major form of Hb in adults and in children over 7 months
    HbA1
  108. 2α, 2γ subunits, in fetus and newborn infants Hb binds Oat lower tension than Hb A
    Fetal Hb (Hb F)
  109. has a higher affinity to oxygen
    Hb F
  110. in the β-globulin chain Glu is replaced by Val (6th AA), an abnormal Hb typical for sickle cell anemia
    Hb S
  111. Oxygen Dissociation curve of Mb
    Hyperbolic
  112. Oxygen dissociation curve of Hb
    Sigmoidal
  113. higher affinity to oxygen shifts to
    left
  114. lower affinity to oxygen shifts to
    right
  115. at tissue ___ of Hb's Ohas been unloaded
    50%
  116. at tissue ___ of Mb's Oremains
    95%
  117. Derivatives of Hemoglobin
    [ODMCCG]

    • Oxyhemoglobin (oxyHb)
    • Deoxyhemoglobin (deoxyHb)
    • Methemoglobin (metHb)
    • Carbonylhemoglobin (HbCO)
    • Carbaminohemoglobin (HbNHCO2-)
    • Glycatedhemoglobin (HbA1c)
  118. Hb with O2
    Oxyhemoglobin (oxyHb)
  119. Hb without O2
    Deoxyhemoglobin (deoxyHb)
  120. contains Fe3+ instead of Fe2+ in heme groups
    Methemoglobin (metHb)
  121. -CO bind with Fe2+ in heme in case of CO poisoning or smoking
    Carbonylhemoglobin (HbCO)
  122. 200x higher affinity to Fe2+ than O2
    Carbon Monoxide (CO)
  123. -CO2 is bound to the N-Terminal amino group of the T form of Hb, it transports CO2 in blood
    Carbaminohemoglobin (HbNHCO2-) Carbamate
  124. formed spontaneously by nonenzymatic reaction with Glc, high in diabetic patients
    Glycatedhemoglobin (HbA1c)
  125. half life of RBC
    60 days
  126. HbA1c  reflects mean blood glucose concentration over ________
    6-8 wks
  127. Provides valuable information for management of Diabetes mellitus
    HbA1c
  128. binds 4 molecules of Oper tetramer, 1 per heme
    Hemoglobin
  129. Hemoglobin features/ characteristics
    • cooperative binding
    • transports Hand CO2
    • Allosteric Protein
    • Binds 4 O2
    • tetramer
    • Bhor effect
    • Affinity for Odependent on pH
    • Lower Oaffinity
  130. Myoglobin features/ characteristics
    • transports Oonly
    • not Allosteric Protein
    • Binds one O2
    • heme/ monomer
    • not dependent on pH
    • higher O2 affinity
  131. Active metabolism in Tissue:
    • ↑ H+
    • ↑ CO2
    • ↓ O2
    • ↓ pH
    • ↑ 2,3-BPG
  132. Active metabolism in lungs:
    • ↓ H+
    • ↓ CO2
    • ↑ O2
    • ↑pH
    • no 2,3-BPG
  133. 2 ways COcan be transported
    • carbamate (15% in venous blood)
    • Bicarbonate (CO+ H2O > carbonic acid > HCO3+ H+)
  134. byproduct of respiration, is transported by hemoglobin from peripheral tissues to the lungs
    CO2
  135. a buffer in erythrocytes
    Hb
  136. High H+ and high CO2 (low pH) promotes the release of O2 to tissues and High O2 will promote the release of H+ and CO2 in the lungs
    Bohr effect
  137. 2 different forms of Hb
    • T-form (tense)
    • R-form (relaxed)
  138. the deoxygenated form, has low Oaffinity, bound with 2,3-BPG, favored by interactions
    T-form
  139. oxygenated form, High O2 affinity,  with bound O
    R-form
  140. enhances the  release of oxygen to tissues
    Low pH (High H+)
  141. increase H+ promoting the unloading of Oxygen to tissues
    High pCO2
  142. promotes unloading of oxygen because it stabilizes the T conformation
    2,3-BPG
  143. effect of increasing BPG concentration
    ODissociation curve shifts to the right (dec in O2 affinity)
  144. When BPG is absent
    O2 Dissociation curve shifts to the left (inc in O2 affinity)
  145. when pH is decreased
    ODC shifts to the right
  146. when pH is increased
    ODC shifts to the left
  147. binding of H+ by Hb (lower pH)
    lowers its affinity for O2
  148. high CO2 levels in the plasma result in a
    ODC shifts to the right
  149. ATP is generated by
    anaerobic glycolysis
  150. used for ion transport across the cell membrane
    ATP
  151. produces 2,3 BPG and lactate
    glycolysis
  152. Disorders caused by production of structurally abnormal Hb
    HEMOGLOBINOPATHIES
  153. example of HEMOGLOBINOPATHIES
    • Sickle-cell anemia
    • thalassemias
  154. a homozygous recessive disorder, inherited from two mutant genes from each parent
    Sickle-cell anemia
  155. sickle cell anemia is characterized by
    • hemolytic anemia
    • susceptibility to infection
  156. Sickle cell trait
    • have one normal and one mutant gene
    • heterozygous
    • RBC contains both HbS and HbA
    • Do not display clinical symptoms and live normal lives
  157. provide protection against malaria parasite Plasmodium falciparum which spends a part of its life cycle in the RBC
    Heterozygous state
  158. Sickle cell trait is prevalent among
    black americans/ african countries
  159. Defective biosynthesis of globin chain, genetic defects of hemolytic anemias
    Thalassemias
  160. inherited autosomal recessive blood diseases
    Thalassemias
  161. are prevalent in population where malaria was endemic - arab americans, people of mediterranean origins and asians
    Thalassemias
  162. genetic defects result in reduced rate of synthesis of alpha and beta globin chain - it causes the formation of abnormal Hb molecule results to anemia
    Thalassemias
  163. due to trauma or massive crash injury myoglobin is released from damaged muscle fiber, Urine becomes dark red
    myoglobinuria
  164. reduction in number or RBC and decrease Hb in  the blood, impaired synthesis of hemoglobin (Fe deficiency) and production of erythrocytes (folic acid, Vit B. deficiency)
    anemia

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