Research yields two 'firsts' regarding protein crucial to human cardiac function

Florida State University physics doctoral student Campion Loong, working with Florida State professors, has achieved significant benchmarks in a study of the human cardiac protein alpha-tropomyosin. The study, "Persistence Length of Human Cardiac Alpha-Tropomyosin Measured by Single Molecule Direct Probe Microscopy," has been published in the journal PLoS ONE. Credit: Bill Lax/FSU Photography Services

Florida State University researchers led by physics doctoral student Campion Loong have achieved significant benchmarks in a study of the human cardiac protein alpha-tropomyosin, which is an essential, molecular-level component that controls the heart's contraction on every beat.

Using an imaging method called , Loong achieved two "firsts": the first direct imaging of individual alpha- molecules, which are very small—roughly 40 nanometers long—and the first demonstrated examples of a measure of the human cardiac protein's flexibility. From there, he established a baseline of how flexible a normal version of the protein is supposed to be in a healthy human heart.

"This basic research is important to broadening our understanding of how the functions normally at the molecular level," Loong said. "The flexibility of alpha-tropomyosin dictates how effectively or properly the heart muscle will contract on each beat and has implications for keeping the heart free of cardiovascular disease.

"Before this study, we did not know how flexible this protein was," Loong said. "Using these results, now we can conduct subsequent studies to compare disease-related mutants of this protein to see how much they deviate from normal versions."

Loong served as the lead author of the paper "Persistence Length of Human Cardiac a-Tropomyosin Measured by Single Molecule Direct Probe Microscopy," which was published in the journal . He conducted the research with physics Professor Huan-Xiang Zhou and biological science Professor P. Bryant Chase, both of Florida State.

When an electrical signal is generated in the heart to make it contract, calcium is released inside each cell. The calcium then binds to a protein called troponin, and that triggers the "flexing movement" of alpha-tropomyosin, which allows another protein called myosin—the motor protein—to interact with the troponin/tropomyosin . This series of events is what generates the heart's contraction that pumps blood. A subsequent removal of calcium inside each heart cell is what relaxes the heart, which allows the heart to fill with blood to be pumped on the next beat.

"Alpha-tropomyosin is a key element that makes the calcium signal either turn the heart on, making it contract, or turn it off, making it relax," Chase said. "There is an optimal range of flexibility of alpha-tropomyosin for the normal heart to function properly. The molecule can be too stiff or it can be too flexible, either of which could lead to cardiovascular disease. What we ultimately think is that evolution has tuned the mechanical properties of these proteins for optimal function in the heart."

add to favorites email to friend print save as pdf

Related Stories

Secrets of water bug wings shed light on heart beats

Dec 07, 2010

A research, led by R.J. Perz-Edwards, Ph.D., of Duke University Medical Center, explains how insect flight muscle works, in particular how insects accomplish something called 'stretch activation,' which has been a scientific ...

Atomic model of tropomyosin bound to actin

Feb 15, 2011

New research sheds light on the interaction between the semi-flexible protein tropomyosin and actin thin filaments. The study, published by Cell Press on February 15th in the Biophysical Journal, provides the first detail ...

Protein identified that helps heart muscle contract

Feb 16, 2010

UCSF researchers have discovered that a protein called B1N1 is necessary for the heart to contract. The findings, published in the Feb. 16 issue of the open access journal PLoS Biology, shed light not only on what makes ...

Muscle weakness: New mutation identified

Jun 14, 2007

New research, published in The Journal of Physiology, has identified a novel mutation associated with muscle weakness and distal limb deformities. The study demonstrates that muscle weakness experienced by persons with a ...

Recommended for you

Gene variant raises risk for aortic tear and rupture

17 hours ago

Researchers from Yale School of Medicine and Celera Diagnostics have confirmed the significance of a genetic variant that substantially increases the risk of a frequently fatal thoracic aortic dissection or full rupture. ...

Considerable variation in CT use in ischemic stroke

18 hours ago

(HealthDay)—For patients with ischemic stroke there is considerable variation in the rates of high-intensity computed tomography (CT) use, according to a study published online April 8 in Circulation: Ca ...

Beating the clock for ischemic stroke sufferers

Apr 17, 2014

A ground-breaking computer technology raises hope for people struck by ischemic stroke, which is a very common kind of stroke accounting for over 80 per cent of overall stroke cases. Developed by research experts at The Hong ...

Risk for nonelective thoracic aortic sx up for uninsured

Apr 16, 2014

(HealthDay)—Uninsured patients have an increased risk of nonelective thoracic aortic operations, and have increased risks of major morbidity or mortality, according to a study published online April 8 in ...

User comments