Related Experiment Video

Updated: Sep 26, 2026

Measurement of Heme Synthesis Levels in Mammalian Cells
09:43

Measurement of Heme Synthesis Levels in Mammalian Cells

Published on: July 9, 2015

Characterization of the heme environmental structure of cytoglobin, a fourth globin in humans

Hitomi Sawai1, Norifumi Kawada, Katsutoshi Yoshizato

  • 1Department of Life Science, Graduate School of Science, Himeji Institute of Technology, 3-2-1 Kouto, Kamigori-cho, Ako, Hyogo 678-1297, Japan.

Biochemistry
|April 30, 2003
PubMed

Insights

Cytoglobin (Cgb), a mammalian globin, binds heme iron via His81 and His113. Its heme pocket structure suggests a role in oxygen storage.

Area of Science:

  • Biochemistry
  • Structural Biology
  • Mammalian Physiology

Background:

  • Cytoglobin (Cgb) is the fourth mammalian globin, but its function remains uncharacterized.
  • Understanding Cgb's structure-function relationship is crucial for elucidating its biological role.

Purpose of the Study:

  • To investigate the axial heme iron coordination in Cytoglobin (Cgb).
  • To characterize the heme pocket environment and its implications for Cgb's proposed oxygen storage function.

Main Methods:

  • Site-directed mutagenesis of six histidine residues to alanine.
  • Optical absorption, resonance Raman, and infrared spectroscopy.
  • Redox potential measurements.

Main Results:

  • His81 (E7) and His113 (F8) imidazole residues act as axial ligands to the heme iron in a hexacoordinate, low-spin state.
  • CO binding to ferrous Cgb involves dissociation of the His81 imidazole, forming three conformers with interactions between CO and His81.
  • Resonance Raman spectra of oxy Cgb show a polar heme environment, indicated by nu(Fe-O2) at 572 cm(-1).

Conclusions:

  • The study elucidates the heme iron coordination and heme pocket structure of Cytoglobin.
  • These structural features support the proposed in vivo oxygen storage function of Cgb.

More Related Videos

T-wave Ion Mobility-mass Spectrometry: Basic Experimental Procedures for Protein Complex Analysis16:40

T-wave Ion Mobility-mass Spectrometry: Basic Experimental Procedures for Protein Complex Analysis

Published on: July 31, 2010

Stability and Structure of Bat Major Histocompatibility Complex Class I with Heterologous β2-Microglobulin11:17

Stability and Structure of Bat Major Histocompatibility Complex Class I with Heterologous β2-Microglobulin

Published on: March 10, 2021

Related Concept Videos

Hemoglobin01:24

Hemoglobin

Hemoglobin is a globular protein made up of four subunits. Two of these subunits are alpha chains, and the other two are beta chains. Each subunit contains a molecule of heme, which has an iron atom and can bind to oxygen. When an oxygen molecule binds to one heme group, it changes the shape of hemoglobin, making it easier for the other heme groups to bind oxygen as well.
When all four heme groups are bound to oxygen, the resulting molecule is called oxyhemoglobin. As a result, arterial blood...
Globular Proteins01:27

Globular Proteins

In organisms, proteins are the most abundant macromolecules. They act as the building blocks of life and play various crucial roles in the body. Proteins can be broadly classified into two distinct subtypes based on their shape and solubilities: globular proteins and fibrous proteins.
Globular proteins serve many important physiological functions, such as acting as enzymes, cellular messengers, and molecular transporters. These roles often require the proteins to be soluble in the aqueous...
Gene Families01:57

Gene Families

Gene families consist of groups of genes proposed to have originated from a common ancestor. Typically these arise through events in which a gene or genes are mistakenly duplicated during cell division. Unlike their parent genes (which are subject to selection pressure to maintain function), these gene copies do not need to preserve their sequences and may evolve at a relatively faster rate.
Occasionally these regions can be adapted to take on new roles within the organism, becoming novel genes...
Structure and Function of Erythrocytes01:29

Structure and Function of Erythrocytes

There are between 4.2 and 6 million erythrocytes, also known as red blood cells, in every microliter of blood. These cells are small, flattened biconcave discs with centers that are depressed.
The erythrocyte plasma membrane is associated with proteins such as spectrin, which forms a flexible cytoplasmic meshwork. This meshwork allows erythrocytes to twist, turn, become cup-shaped, and regain their biconcave shape as they pass through narrow capillaries. Additionally, erythrocytes can form...
Protein and Protein Structure02:39

Protein and Protein Structure

Proteins are one of the most abundant organic molecules in living systems and have the most diverse range of functions of all macromolecules. Proteins may be structural, regulatory, contractile, or protective. They may serve in transport, storage, or membranes; or they may be toxins or enzymes. Their structures, like their functions, vary greatly. They are all, however, amino acid polymers arranged in a linear sequence.A protein's shape is critical to its function. For example, an enzyme can...
Globular and Fibrous Proteins02:21

Globular and Fibrous Proteins

Many proteins can be classified into two distinct subtypes - globular or fibrous. These two types differ in their shapes and solubilities.
Globular proteins are also known as spheroproteins and typically are approximately round in shape. They contain a mix of amino acid types and contain differing sequences in their primary structures. Globular proteins have many different functions, such as enzymes, cellular messengers, and molecular transporters. These roles often require the proteins to be...