As shown in the figures to the left and right, most DNA of living things on the earth twists as a "right-hand screw". This is the same direction as a regular wood or metal screw. Many artists will flip a picture of DNA over and reverse the twist. Although left-handed Z-DNA has been demonstrated by X-ray crystallography and scanning tunnel microscopy (STM), it only recently was established that it occurs in vivo (Schwartz et al Science 1999 Jun 11;284(5421):1841-5, New York Times, June 29, 1999).

Thanks to Boris Steipe for this figure.

See the figure to the right, which compares normal B-DNA found in cells to the rare Z-DNA, which is the same molecule twisted the other way. Furthermore, the structure of this left-handed Z-DNA is quite different from a mirror image of B-form DNA. So most of these inverted twist pictures are incorrect. This error has become so pervasive that even well-known scientists, major scientific journals and institutes make it. For several years I was collecting these cases by tossing them into a file. On 1996 February 14, I was stunned and embarrassed that my file had grown enormous, so I created this page to alert people to the problem. (Thanks to Eric Putz at my alma mater CU's MCDB for permission to use the rotating DNA.)

See the Right Handed DNA Hall of Fame and my home page on molecular information theory too!

For your first visit to the Left Handed Hall of Fame page I suggest that you follow the story over all of the years. After that you can look at each year individually from the table below. Note: just because a year has gone by does not mean we haven't found more examples for that year!

1997 and 1998 were bumper crop years
and 1999 beat them more than 2 fold. 2000 was a record year, thanks to help from friends around the world (60 of the 97 cases, 63%!). 2001 exceeded even that record! 2002 was lower - are we making headway?

Coda

None of the statements on this page are intended to endorse or favor any product over other equivalent products on the market.

When a source can be identified, permission has been requested to reproduce all graphics. If someone knows who made that cute mouse (which I picked up from somewhere on the net), please tell me.

Contributions

It helps if you check through the previous entries to see if you have been scooped, as I do not repeat (even for really egregious cases).

DO NOT SEND IMAGES BY EMAIL!!! If you would like to contribute examples that are on the web, please send me precise evidence that documents the case, along with all reference materials that are available. Precise web pointers are appreciated as it saves me time. If there is an image on the web just tell me where it is, please NEVER send me images that I can get from the web! I have to check them anyway and I use wget or curl to grab them (curl is part of macOS). Let me put that another way: I cannot use graphics sent to me. I only use ones I can verify from the web.

Finally, PLEASE DO NOT SEND ME DOC FILES!

Also please indicate whether you would like to be acknowledged on this page. Your name will be listed with your email address if you do not tell me. Since I don't want to have to recall previous rules for people, please tell me how you would like to be listed each time. You may pick an alias such as Gorilla Guerilla (which is already taken).

Web Sites: For web sites, it helps a lot if you email to me three URLs:

• The web site page where you found the image.
• The url of the image itself.
• The url of a page that gives the email address of the contact for obtaining permissions.

Printed Sources: I no longer accept physical examples.

Books: For books please send URL links to pages that include this information:

• the front cover
• the inside page that includes the ISBN and other publication details
• the pages you have found the examples on

Image Policy