Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

Nucleophilic Substitution Reactions02:34

Nucleophilic Substitution Reactions

Historical perspective
In 1896, the German chemist Paul Walden discovered that he could interconvert pure enantiomeric (+) and (-) malic acids through a series of reactions. This conversion suggested the involvement of optical inversion during the substitution reaction. Further, in 1930, Sir Christopher Ingold described for the first time two different forms of nucleophilic substitution reactions, which are known as SN1 (nucleophilic substitution unimolecular) and SN2 (nucleophilic substitution...
Aldehydes and Ketones with Amines: Enamine Formation Mechanism01:14

Aldehydes and Ketones with Amines: Enamine Formation Mechanism

Enamine formation involves the addition of carbonyl compounds to a secondary amine through a series of reactions. The mechanism begins with the generation of carbinolamine, a nucleophilic attack followed by several proton transfer reactions. The hydroxyl group of the carbinolamine is converted into water to make a better leaving group that can push the reaction forward by eliminating a water molecule. In enamine formation, the last step involves the abstraction of a proton from the α carbon to...
Introduction to Mechanisms of Enzyme Catalysis01:13

Introduction to Mechanisms of Enzyme Catalysis

For many years, scientists thought that enzyme-substrate binding took place in a simple "lock-and-key" fashion. This model stated that the enzyme and substrate fit together perfectly in one instantaneous step. However, current research supports a more refined view scientists call induced fit. The induced-fit model expands upon the lock-and-key model by describing a more dynamic interaction between enzyme and substrate. As the enzyme and substrate come together, their interaction causes a mild...
Introduction to Mechanisms of Enzyme Catalysis01:13

Introduction to Mechanisms of Enzyme Catalysis

For many years, scientists thought that enzyme-substrate binding took place in a simple "lock-and-key" fashion. This model stated that the enzyme and substrate fit together perfectly in one instantaneous step. However, current research supports a more refined view scientists call induced fit. The induced-fit model expands upon the lock-and-key model by describing a more dynamic interaction between enzyme and substrate. As the enzyme and substrate come together, their interaction causes a mild...
Structure of Amines01:19

Structure of Amines

The hybridized nitrogen atom in amines possesses a lone pair of electrons and is bound to three substituents with a bond angle of around 108°, which is less than the tetrahedral angle of 109.5°. However, the C–N–H bond angle is slightly larger at 112°, with a carbon–nitrogen bond length of 147 pm. This carbon–nitrogen bond length of of amines is longer than the carbon–oxygen bond of alcohols (143 pm) but shorter than alkanes’ carbon–carbon bond (154 pm). These aspects are illustrated in Figure...
Acidity of 1-Alkynes02:42

Acidity of 1-Alkynes


The acidic strength of hydrocarbons follows the order: Alkynes > Alkenes > Alkanes. The strength of an acid is commonly expressed in units of pKa — the lower the pKa, the stronger the acid. Among the hydrocarbons, terminal alkynes have lower pKa values and are, therefore, more acidic. For example, the pKa values for ethane, ethene, and acetylene are 51, 44, and 25, respectively, as shown here.

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

The <i>Escherichia coli</i> Radical SAM Enzyme YhcC Substitutes for the FAD-Dependent Oxidase Activity of MnmC in 5-Methylaminomethyl-2-Thiouridine tRNA Modification Under Anaerobic Conditions.

bioRxiv : the preprint server for biology·2026
Same author

Electrochemical characterization of photo-driven hole-scavenging by cadmium sulfide quantum dot-nitrogenase biohybrid complexes.

Bioelectrochemistry (Amsterdam, Netherlands)·2026
Same author

Sulfite Is Not Required for N<sub>2</sub> Reduction Catalyzed by Mo-Nitrogenase.

Journal of the American Chemical Society·2026
Same author

Intricacies in iron-sulfur cluster function and biogenesis: functional versatility, sulfur sources, and enzyme specificity.

RSC chemical biology·2026
Same author

Mechanistic Insights into Dinitrogen Reduction to Ammonia in Light-Controlled Nanocrystal:Nitrogenase Complexes.

Accounts of chemical research·2026
Same author

Trafficking of a nitrogenase FeMo-cofactor assembly intermediate.

Nature chemical biology·2026

Related Experiment Video

Updated: Jul 13, 2026

Protein Film Infrared Electrochemistry Demonstrated for Study of H2 Oxidation by a [NiFe] Hydrogenase
10:01

Protein Film Infrared Electrochemistry Demonstrated for Study of H2 Oxidation by a [NiFe] Hydrogenase

Published on: December 4, 2017

Alkyne substrate interaction within the nitrogenase MoFe protein.

Patricia C Dos Santos1, Suzanne M Mayer, Brett M Barney

  • 1Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, USA.

Journal of Inorganic Biochemistry
|July 6, 2007
PubMed
Summary

Nitrogenase enzymes use FeMo-cofactor for nitrogen fixation. Modifying specific protein residues alters how substrates like alkynes bind, enabling new reactions and supporting current models of substrate interaction.

More Related Videos

X-Ray Crystallography to Study the Oligomeric State Transition of the Thermotoga maritima M42 Aminopeptidase TmPep1050
11:27

X-Ray Crystallography to Study the Oligomeric State Transition of the Thermotoga maritima M42 Aminopeptidase TmPep1050

Published on: May 13, 2020

Synthesis of Metal Nanoparticles Supported on Carbon Nanotube with Doped Co and N Atoms and its Catalytic Applications in Hydrogen Production
08:40

Synthesis of Metal Nanoparticles Supported on Carbon Nanotube with Doped Co and N Atoms and its Catalytic Applications in Hydrogen Production

Published on: December 6, 2021

Related Experiment Videos

Last Updated: Jul 13, 2026

Protein Film Infrared Electrochemistry Demonstrated for Study of H2 Oxidation by a [NiFe] Hydrogenase
10:01

Protein Film Infrared Electrochemistry Demonstrated for Study of H2 Oxidation by a [NiFe] Hydrogenase

Published on: December 4, 2017

X-Ray Crystallography to Study the Oligomeric State Transition of the Thermotoga maritima M42 Aminopeptidase TmPep1050
11:27

X-Ray Crystallography to Study the Oligomeric State Transition of the Thermotoga maritima M42 Aminopeptidase TmPep1050

Published on: May 13, 2020

Synthesis of Metal Nanoparticles Supported on Carbon Nanotube with Doped Co and N Atoms and its Catalytic Applications in Hydrogen Production
08:40

Synthesis of Metal Nanoparticles Supported on Carbon Nanotube with Doped Co and N Atoms and its Catalytic Applications in Hydrogen Production

Published on: December 6, 2021

Area of Science:

  • Biochemistry
  • Enzymology
  • Bioinorganic Chemistry

Background:

  • Nitrogenase catalyzes nitrogen fixation, converting N(2) to ammonia.
  • The FeMo-cofactor within the MoFe protein is the active site for substrate reduction.
  • Substrate interaction mechanisms with FeMo-cofactor remain incompletely understood.

Purpose of the Study:

  • Investigate the role of MoFe protein residues in substrate access to the FeMo-cofactor.
  • Determine how specific amino acid substitutions affect alkyne reduction by nitrogenase.
  • Refine the model of alkyne binding and reduction within the nitrogenase active site.

Main Methods:

  • Site-directed mutagenesis of MoFe protein alpha-70(Val) and alpha-191(Gln) residues.
  • Enzymatic assays measuring alkyne reduction rates and product formation.
  • Spectroscopic studies to probe substrate-enzyme interactions.

Main Results:

  • Substitution of alpha-70(Val) with glycine enhanced 1-butyne reduction but not 2-butyne reduction.
  • A double mutant (alpha-70(Ala)/alpha-191(Ala)) facilitated significant 2-butyne reduction to 2-cis-butene.
  • These findings suggest alkynes bind side-on to Fe6, independent of a terminal acidic proton.

Conclusions:

  • Amino acid substitutions can engineer nitrogenase activity towards non-physiological substrates.
  • The results support a model of side-on alkyne binding to Fe6 within the FeMo-cofactor.
  • This work advances understanding of enzyme active site engineering and substrate recognition.