Sigma Xi Undergraduate Showcase 2
Location
Knight Auditorium
Event Website
https://nova.libcal.com/event/17637267
Start Date
10-11-2026 12:30 PM
End Date
10-11-2026 1:20 PM
Description
Krisha Patel
Leonardo Gomes
Title: Structure, Function, and Medical Applications of the Botulinum Neurotoxin type A (BoNT/A)
The biotherapeutic known as botulinum neurotoxin type A (BoNT/A) is produced by Clostridium botulinum and is famous as one of the most poisonous biological toxins. However, when used in controlled quantities, it can be a very useful treatment and is applied both in the management of muscle disorders and for the purpose of smoothing out wrinkles. The objective of this presentation is to describe how BoNT/A works at a molecular level by connecting its protein structure and catalytic activity to the different medical and cosmetic uses it has.
The active toxin is a 150 kDa protein made up of two chains joined together by a disulfide bond, specifically a 100 kDa Heavy Chain (Hc) and a 50 kDa Light Chain (Lc). The Heavy Chain first binds to motor neurons via a 'dual-receptor' system by interacting with both the membrane gangliosides and the synaptic vesicle protein SV2. After the nerve cell has taken up the toxin by endocytosis, the acidic condition inside the endosome causes the translocation domain (HN) of the Heavy Chain to change shape and to form a channel, thus enabling the catalytic Light Chain to transit across the membrane and enter the cytoplasm.
Inside the cell, the Light Chain acts as a zinc metalloprotease having the typical HEXXH +E catalytic sequence and cuts one peptide bond between Gln197 and Arg198 on SNAP-25, thus removing nine amino acids. Even though the fragment which is removed is small, this cleavage prevents the SNARE complex from assembling properly and consequently stops the release of acetylcholine, causing a temporary paralysis of the muscle without killing the neuron.
The presentation also examines how this molecular blockade is put into use in real-life situations. Apart from being used to relax facial muscles for cosmetic anti-aging and helping to alleviate painful muscle spasms in conditions like cervical dystonia, BoNT/A is employed to stop over-sweating (hyperhidrosis) by blocking the cholinergic signals which get to the sweat glands. It has a number of interesting cosmetic applications as well, for instance the well-known treatment called "hair Botox". This presentation demonstrates that by studying protein structure and enzyme catalysis we can turn a deadly bacterial weapon into a precise medical tool.
About the presenter:
Leonardo Gomes is an Honors in Major (Biology)senior undergraduate student at Nova Southeastern University majoring in Biology with minors in Business and Pre-Health. Through his coursework, he has developed a strong interest in understanding human health and pharmacology, with a particular focus on drug mechanisms and the biochemistry of therapeutic proteins. Outside the classroom, he has completed extensive clinical shadowing alongside plastic and reconstructive surgeons, where he gained insight into patient care, surgical procedures, and the day-to-day realities of aesthetic and reconstructive surgery. These experiences solidified his fascination with aesthetic and reconstructive medicine, as well as the practical applications of injectable pharmaceuticals. Following graduation, he plans to attend medical school to pursue a career as a plastic surgeon, hoping to combine a dedication to surgical technique and clinical care with his background in biochemistry and healthcare.
Tej Chaudhari
Sigma Xi Undergraduate Showcase 2
Knight Auditorium
Krisha Patel
Leonardo Gomes
Title: Structure, Function, and Medical Applications of the Botulinum Neurotoxin type A (BoNT/A)
The biotherapeutic known as botulinum neurotoxin type A (BoNT/A) is produced by Clostridium botulinum and is famous as one of the most poisonous biological toxins. However, when used in controlled quantities, it can be a very useful treatment and is applied both in the management of muscle disorders and for the purpose of smoothing out wrinkles. The objective of this presentation is to describe how BoNT/A works at a molecular level by connecting its protein structure and catalytic activity to the different medical and cosmetic uses it has.
The active toxin is a 150 kDa protein made up of two chains joined together by a disulfide bond, specifically a 100 kDa Heavy Chain (Hc) and a 50 kDa Light Chain (Lc). The Heavy Chain first binds to motor neurons via a 'dual-receptor' system by interacting with both the membrane gangliosides and the synaptic vesicle protein SV2. After the nerve cell has taken up the toxin by endocytosis, the acidic condition inside the endosome causes the translocation domain (HN) of the Heavy Chain to change shape and to form a channel, thus enabling the catalytic Light Chain to transit across the membrane and enter the cytoplasm.
Inside the cell, the Light Chain acts as a zinc metalloprotease having the typical HEXXH +E catalytic sequence and cuts one peptide bond between Gln197 and Arg198 on SNAP-25, thus removing nine amino acids. Even though the fragment which is removed is small, this cleavage prevents the SNARE complex from assembling properly and consequently stops the release of acetylcholine, causing a temporary paralysis of the muscle without killing the neuron.
The presentation also examines how this molecular blockade is put into use in real-life situations. Apart from being used to relax facial muscles for cosmetic anti-aging and helping to alleviate painful muscle spasms in conditions like cervical dystonia, BoNT/A is employed to stop over-sweating (hyperhidrosis) by blocking the cholinergic signals which get to the sweat glands. It has a number of interesting cosmetic applications as well, for instance the well-known treatment called "hair Botox". This presentation demonstrates that by studying protein structure and enzyme catalysis we can turn a deadly bacterial weapon into a precise medical tool.
About the presenter:
Leonardo Gomes is an Honors in Major (Biology)senior undergraduate student at Nova Southeastern University majoring in Biology with minors in Business and Pre-Health. Through his coursework, he has developed a strong interest in understanding human health and pharmacology, with a particular focus on drug mechanisms and the biochemistry of therapeutic proteins. Outside the classroom, he has completed extensive clinical shadowing alongside plastic and reconstructive surgeons, where he gained insight into patient care, surgical procedures, and the day-to-day realities of aesthetic and reconstructive surgery. These experiences solidified his fascination with aesthetic and reconstructive medicine, as well as the practical applications of injectable pharmaceuticals. Following graduation, he plans to attend medical school to pursue a career as a plastic surgeon, hoping to combine a dedication to surgical technique and clinical care with his background in biochemistry and healthcare.
Tej Chaudhari
https://nsuworks.nova.edu/biolectures/2026-2027/Schedule/8