Assimilation Reactions and Energy Release

Energy Utilization in Nonbiosynthetic Processes

            Heat production from metabolic activities

                        culture temperature rises--industrial fermentations

                        ATP’ase eliminates excess ATP and regulates energy

            Motility--up to 10% used for flagellar motion

                        Mg-dependent ATP’ase at membrane--flagella origin

            Transport of Nutrients

                        Passive diffusion--water and some lipid soluble mole.

                                    Brownian movement

                        Facilitated diffusion--protein carriers (porter)

                                    Concentration gradient

                        Group translocation--chmical modification--energy

                                    HPr (heat stable carrier protein)

                                                activated by phosphorylation

                                                phosphoenolpyruvate (PEP)

                                    Unidirectional transport

                                                carrier affinity difference (transmem.)

                                    Conversions associated with inner membrane

                                                adenine  à AMP

                        Active transport--sugars, amino acids, nucleotides

                                    Steps of active transport

1)      binding of solute to carrier

2)      translocation of solute carrier complex

3)      affinity change in protein carrier

Energy Utilization in Biosynthetic Processes

            ATP used for chemical conversions

            Synthesis of macromolecules

                        Structure of peptidoglycan (polymer)

                                    Gram positive--large conc. of peptidoglycans

                        Building blocks

                                    acetylglucosamine (AGA)

                                    acetylmuramic acid (AMA)

                                    peptide (4 to 5 amino acids) D-isomer config.

                        Structure--polysaccharide backbone

                                    alternating AGA and AMA units with--

                                    short peptide chains projecting from AMA

                                    cross bridges between lysine or DPM

                                                diaminopimelic acid

                        Activation of peptidoglycan precursor

                                    Medium:  Glu, Amm. sulfate, and mineral salts

                                    Derivative of AMA

                                                Activation of sugars --attach UDP

                                                            uridine diphosphate


                        Synthesis of peptidoglycans

1)      amino acids attach to AMA precursor--ATP/Mg

2)      AMA-UDP coupled to membrane phospholipid bactoprenol

3)      AGA (AGA-UDP) couples with AMA-UDP

bridging of peptide may occur

4)      AGA-AMA-UDP (attached to membrane) carried outside of

cell membrane

cross linking occurs

            Organic synthesis in chemoautotrophic bacteria

                        Chemoautotrophs--inorganic energy/carbon dioxide

                                    energy by oxidation of hydrogen, ammonia, nitrite, thiosulfate

                                    Energetic disadvantage

                                                enters at cytochrome c

                                                            reduces amount of ATP created

                                                            no reducing power of NADPHH

                                                ATP-dependent NADPH (reversed e- flow)

                                                            ATP breakdown provides energy

                                                                        electromotive potential

                                                                        reduction of NADP

                                                                                    Calvin cycle