Author: Arnout Pieter KalverdaPublisher:
ISBN:
Category :
Languages : en
Pages : 141
Book Description
Structure and Dynamics of Type 1 Blue Copper Proteins
Author: Arnout Pieter KalverdaPublisher:
ISBN:
Category :
Languages : en
Pages : 141
Book Description
Structure-function Analysis of Blue Copper Proteins
Author: Jeremy Daven KingPublisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 117
Book Description
Cofactors extend the chemistry of life. Redox reactions in photosynthesis, nitrogen fixation, and other metabolic pathways depend on metal cofactors. Copper is an essential element in biology, participating in redox reactions and biological catalysis. Copper proteins are classified by their copper centers as type-1, type-2, type-3, CuA, CuB, or Cuz. Type-1 proteins, such as azurin or plastocyanin, are primarily involved in electron transport. Type-1 centers are the most studied copper site at the spectroscopic and structural level. In the type-1 center, the copper cofactor is coordinated by a cysteine, two histidines, and generally a weak axial methionine. This coordination geometry gives rise to several ligand-to-metal charge-transfer transitions, producing a characteristic blue or green type-1 spectrum. In "blue" type-1 copper proteins, the cysteine-copper bond is exceptionally small (2.1 Å) and the methionine-copper bond is abnormally long (2.9 Å). In green type-1 copper proteins, the cysteine-copper bond elongates and the methionine-copper bond contracts. The redox range varies from +83 mV to over +1000 mV. Protein tuning modulates the large variations observed in the redox range and spectral properties. The mechanism of protein tuning is poorly understood. In chapter 2, I characterize a family of four blue copper proteins called auracyanins. The auracyanins, named A-D, were found to have a redox range from +83 mV to +423 mV, and range in color from blue to green. In chapter 3, I take advantage of the tuning variations within the auracyanin family to map the spectral changes to the protein-protein interaction domain. The protein-protein interaction domain has never previously been implicated in protein tuning. These results likely explain how seemingly energetically uphill electron transfer reactions commonly occur with copper proteins. In chapter 4, I perform mutagenesis on the weak axial ligand in auracyanin D. Auracyanin D is a green copper protein, and has the lowest redox potential ever measured for a copper protein. Significant work has been done on axial ligands in blue type-1 copper proteins, but never in green type-1 copper proteins. I found that substitutions to the axial ligand in green copper sites are much larger than their blue copper protein counterparts. In chapter 5, I conclude with a computational approach showing significant variation in the coordinating ligands of uncharacterized copper proteins. I believe examination of these proteins by a reverse biochemical approach will add more clarity to the role of protein tuning and expand the limits of copper tuning.
Dynamics of Blue Copper Proteins
Author: David Henry EhrensteinPublisher:
ISBN:
Category :
Languages : en
Pages : 156
Book Description
Studies of small molecules binding to heme proteins have yielded a large amount of information about protein dynamics and conformational substates (CS) in proteins. However, heme proteins are very similar in their active site structures, and relatively little work exists on non-heme proteins which is directly comparable to the heme protein experiments. We have therefore studied the binding of NO to three blue copper proteins, a class of proteins which lack a heme group and have a different structural motif from that of heme proteins. The proteins are azurin (Az), halocyanin (Ha), and nitrite reductase (NiR). NO binds reversibly to a type 1 copper active site in these proteins, and it can be photodissociated. We measured the kinetics of rebinding following photodissociation over a wide range of temperature (40-280 K) and time ($10sp{-6}-10sp2$ s) and compare the results with those of heme proteins. We find that the rebinding kinetics share many basic properties with heme protein kinetics. In all three proteins, at the lowest temperatures, rebinding is non-exponential in time, which in AzNO and HaNO is attributed to a Gaussian distribution of activation enthalpies of rebinding from a site close to the copper. Above 200 K, rebinding to Az and Ha is exponential in time and dependent upon NO concentration, implying that at these temperatures, fluctuations between CS are much faster than rebinding and that rebinding is bimolecular. HaNO rebinding also exhibits two additional kinetic processes. The first one we model using an additional distribution of rebinding barriers having a non-Gaussian shape. We describe the second additional process using a relaxation model, which is based on a successful description of myoglobin-CO kinetics. The flash photolysis kinetics of NiRNO display two distinct processes, one slow and one fast, with different physical bases. The slow process we attribute to NO rebinding, and we assign the fast process to intra-molecular electron transfer and describe it with a Gaussian distribution of enthalpy barriers. The fast process also directly demonstrates the phenomenon of fluctuational averaging, which has been previously observed in heme proteins. We show that the simplest model of this effect correctly predicts, within uncertainties, the average rate coefficient at high temperature. Finally, we propose a model for the NO-bound copper coordination geometry and describe some implications of it. We conclude by summarizing the properties these blue copper proteins share with heme proteins and show that they not only confirm much of our understanding of protein dynamics but also exhibit a wider range of parameters than do heme proteins.
Metal Sites in Proteins and Models
Author: H.A.O. HillPublisher: Springer Science & Business Media
ISBN: 9783540655534
Category : Science
Languages : en
Pages : 222
Book Description
Biological chemistry is a major frontier of inorganic chemistry. Three special volumes devoted to Metal Sites in Proteins and Models address the questions: how unusual ("entatic") are metal sites in metalloproteins and metalloenzymes compared to those in small coordination complexes? and if they are special, how do polypeptide chains and co-factors control this? The chapters deal with iron, with metal centres acting as Lewis acids, metals in phosphate enzymes, with vanadium, and with the wide variety of transition metal ions which act as redox centres. They illustrate in particular how the combined armoury of genetics and structure determination at the molecular level are providing unprecedented new tools for molecular engineering.
Copper Proteins and Copper Enzymes
Author: Rene LontiePublisher: CRC Press
ISBN: 1351079352
Category : Medical
Languages : en
Pages : 233
Book Description
These volumes of Copper Proteins and Copper Enzymes are intended to describe the contemporary spectroscopy and other biophysical chemistry now being applied to copper proteins in order to determine the structures of their active sites. Several chapters of the treatise describe the functional understanding which is emerging from the new work. The authors are all major contributors to research progress on copper proteins and the volumes will be found to be definitive and authoritative.
Investigating the Structure-function Relationships in Blue Copper Proteins
Author: John Ke MaThe Electronic Structure of the Blue Copper Proteins
Author: Kevin Wade PenfieldCopper Proteins
Author: Thomas G. SpiroPublisher: John Wiley & Sons
ISBN:
Category : Science
Languages : en
Pages : 388
Book Description
An Interpretation of the Three Dimensional Structure of Blue Copper Protein
Author: Rachel BramsonPublisher:
ISBN:
Category : Copper proteins
Languages : en
Pages : 164
Book Description
Excited State Structure and Dynamics from Absolute Resonance Raman Intensities
Author: Mary Katherine LawlessPublisher:
ISBN:
Category :
Languages : en
Pages : 538
Book Description